Foreign Minister Julie Bishop also said: "We extend our deep condolences and sympathy for the victims and their families, and the Iranian people." The Australian Embassy in Tehran was monitoring the situation and was in contact with Iranian authorities to determine whether any Australians were affected.
The White House has released a statement from President Donald Trump condemning the terrorist attacks in Tehran and offering condolences, but also implying that Iran is itself a sponsor of terrorism.
"We grieve and pray for the innocent victims of the terrorist attacks in Iran, and for the Iranian people, who are going through such challenging times," the statement said. "We underscore that states that sponsor terrorism risk falling victim to the evil they promote."
An Iranian security official says the assailants in the deadly attacks in Tehran Wednesday were Iranian nationals.
The website of independent Shargh daily quoted Reza Seifollahi, an official in the country's Supreme National Security Council, as saying the operatives in the dual attacks that killed at least 12 people were from Iran. He did not elaborate.
The Islamic State group has claimed responsibility for the attacks.
The U.N. Security Council is condemning "the barbaric and cowardly terrorist attacks" in Tehran in the strongest terms and is calling for the organizers, perpetrators and financiers to be brought to justice.
The council statement, drafted by Japan on behalf of countries in the Asia-Pacific region and approved Wednesday by all 15 council members including the United States, denounced the "reprehensible acts of terrorism."
The U.N.'s most powerful body used almost the same language it has used in statements condemning previous terrorist attacks.
The Islamic State group claimed responsibility for Wednesday's attacks on Iran's Parliament and the tomb of Iran's revolutionary leader, Ayatollah Ruhollah Khomeini, which killed at least 12 and injured at least 40 people.
The Security Council reaffirmed that "terrorism in all its forms and manifestations constitutes one of the most serious threats to international peace and security" and said "any acts of terrorism are criminal and unjustifiable."
The council reiterated that all countries are required to combat threats to international peace and security caused by "terrorist acts" by "all means." And it stressed "the need to take measures to prevent and suppress the financing of terrorism, terrorist organizations and individual terrorists."
The police chief of Tehran says that five suspects have been detained following the deadly dual attacks in Tehran that killed at least 12 people and wounded more than 40.
Gen. Hossein Sajedinia told the semi-official ISNA news agency Wednesday night that police are interrogating the suspects. He did not elaborate, but said Tehran is safe and police and other security forces are deployed and closely monitoring the capital.
The attacks were claimed by the Islamic State group.
U.N. Secretary-General Antonio Guterres is strongly condemning the terrorist attacks in Tehran and calling for those responsible to be brought to justice.
Spokesman Stephane Dujarric told reporters Wednesday that "all countries must work together in fighting terrorism while upholding the universal rights and values that bind the global community."
He said Guterres extends "sincere condolences" to the government of Iran and the families of those killed, and wishes a speedy recovery to the injured.
The United States is condemning what it calls "terrorist attacks" in the Iranian capital of Tehran.
State Department spokeswoman Heather Nauert says the U.S. is sending thoughts and prayers to the Iranian people following attacks that struck Iran's parliament and the mausoleum of its modern founder. Nauert says the U.S. is expressing condolences to the victims and their families.
The Islamic State group has claimed responsibility for the attack
Nauert says that "the depravity of terrorism has no place in a peaceful, civilized world."
Iran and the U.S. don't maintain diplomatic relations and the Trump administration has emphasized the need to counter Iran's influence.
Despite the U.S. condemnation of the attack, the Senate was considering a possible procedural vote Wednesday afternoon on a new set of Iranian sanctions. Some Democrats are pushing for the vote to be delayed out of consideration for what happened in Tehran.
A top Emirati diplomat has offered his condolences to Iran over Islamic State-claimed attacks on its capital, Tehran.
Emirati Minister of State for Foreign Affairs Anwar Gargash told The Associated Press on Wednesday that the United Arab Emirates rejected and condemned all terrorist acts.
However, Gargash said Gulf nations and Iran's government remained "poles apart" from each other on political and security matters. He warned: "The Iranian government should not use the attack in a very polarized situation against Saudi Arabia or claim that Saudi Arabia is somehow linked to the attack, because it isn't."
He added: "It's an attack on civilians that is a crime and that should be condemned by all civilized people."
The Iranian Revolutionary Guard released a statement Wednesday evening indirectly blaming Saudi Arabia for the attacks.
U.N. diplomats say Japan has circulated a draft statement condemning the attacks by Islamic State extremists in Tehran to members of the Security Council.
The diplomats, speaking on condition of anonymity because the statement has not yet been released, said Japan submitted the draft Wednesday on behalf of Asian and Pacific members and it was being discussed by council members.
The diplomats said the statement includes language on extremist attacks previously agreed upon by the council.
This language reaffirms that "terrorism in all its forms and manifestations constitutes one of the most serious threats to international peace and security" and underlines the need to bring the perpetrators, organizers, financiers and sponsors of an attack to justice.
It also states that "any acts of terrorism are criminal and unjustifiable, regardless of their motivation, wherever, whenever and by whomsoever committed."
—Edith M. Lederer at the United Nations
Iran's Powerful Revolutionary Guard is indirectly blaming Saudi Arabia for the twin terrorist attacks in Tehran.
The statement Wednesday evening stops short of alleging direct Saudi involvement but calls it "meaningful" that the attacks took place about one week after U.S. President Donald Trump travelled to Saudi Arabia and strongly asserted American support for Riyadh.
The statement says that Saudi Arabia "constantly supports takfiri terrorists" including the Islamic State group and the IS claim of responsibility "reveals their (Saudi Arabia's) hand in this barbaric action."
The statement concludes that the "spilled blood of the innocent will not remain unavenged."
German Foreign Minister Sigmar Gabriel has condemned the attacks in Tehran, saying "once against unscrupulous criminals have dragged many innocent people to their death."
Gabriel said in a statement Wednesday that "where terror knows no borders, sympathy and humanity must have no barriers."
He said Germany "grieves with the people in Iran" and expressed hope that those injured would fully recover soon.
Germany is one of the six world powers that were part of the nuclear deal with Iran.
Pakistan has condemned twin attacks on Iran's parliament and a shrine to its revolutionary leader.
The Foreign Office said Islamabad stands in solidarity with the people of Iran after Wednesday's attacks, which killed at least 12 people and were claimed by the Islamic State group.
Pakistan shares a porous border with Iran, and the two sides agreed to boost security last month after gunmen killed 10 Iranian border guards.
Syria has condemned the "terrorist attacks" that targeted the Iranian parliament and the mausoleum of revolutionary leader Ayatollah Ruhollah Khomeini.
The Foreign Ministry says Wednesday's attacks were backed by various governments, without specifying. The attacks were claimed by the Islamic State group, which Syria routinely claims, without evidence, is backed by Western and other powers that want to remove President Bashar Assad from power.
Iran has been a key backer of Assad throughout Syria's six-year-long civil war. It has shored up the government with arms and energy transfers and sent elite fighters, top military advisers, and thousands of militiamen to bolster Assad's forces.
Iran and Syria both cast the conflict as a struggle against Sunni Islamist terrorism. Their opponents instead blame the two governments for casting the conflict in starkly sectarian terms.
Russian President Vladimir Putin has offered his condolences after twin attacks on Iran's parliament and a shrine to its revolutionary leader, vowing aid in the fight against international terrorism.
In a message released by the Kremlin after Wednesday's attacks, Putin said Russia "resolutely condemns" the violence.
Putin said the attacks underscore the need for deeper international cooperation to fight terrorism and confirmed Moscow's willingness to aid Iran.
The Islamic State group claimed the attacks, marking the first time it has taken responsibility for an assault in Iran. The Sunni extremists are battling Iranian and Russian-backed forces in Syria and Iraq.
An Iranian state-run news website says 12 people were killed and 42 wounded in attacks on the country's parliament and the shrine of its revolutionary leader.
Mizan Online, which is affiliated with the judiciary, attributed the toll from Wednesday's attacks to Pirhossein Kolivand, the head of Iran's emergency department.
Several gunmen and suicide bombers attacked parliament and the shrine to Ayatollah Ruhollah Khomeini, setting off an hours-long siege at the legislature that ended with four attackers dead. The Islamic State group claimed the attacks.
A 24-second video released by the Islamic State group's Aamaq news agency purports to show the siege of Iran's parliament.
The video, circulated online, shows a gunman and a bloody, lifeless body of a man lying on the ground next to a desk.
A voice on the video praises God and says in Arabic: "Do you think we will leave? We will remain, God willing." Another voice repeats the same words. The two appeared to be parroting a slogan used by IS spokesman Abu Mohammad al-Adnani, who was killed in Syria last year.
IS rarely releases statements or other media about ongoing operations. The video emerged before Iranian media reported that the siege had ended, with four attackers killed.
The group has claimed the attack on Iran's parliament and another on the shrine of Ayatollah Ruhollah Khomeini on Wednesday, which killed at least two and wounded more than 30 people.
Iran's semi-official Tasnim news agency says the siege at parliament is over and that four attackers have been killed.
Gunmen and suicide bombers attacked parliament and the shrine of Ayatollah Ruhollah Khomeini on Wednesday, killing at least two security guards and wounding more than 30 people. The Islamic State group claimed both attacks.
The attack on parliament, which was in session at the time, lasted more than three hours. Police surrounded the building and gunfire could be heard from outside.
It marked the first time IS has claimed an attack in Iran. The Sunni extremist group is at war with Iranian-backed forces in Syria and Iraq, and views Iran's Shiite majority as apostates deserving of death.
Iran's state-run IRNA news agency says two security guards have been killed and more than 30 people wounded in attacks on the parliament building and the shrine of Ayatollah Ruhollah Khomeini.
Assailants armed with Kalashnikov rifles stormed the parliament building Wednesday and one of the attackers blew himself up inside, where a session had been in progress. Another group of attackers, including a second suicide bomber, struck the shrine.
The Islamic State group claimed the attack, marking the first time it has taken responsibility for an assault in Iran. The Sunni extremist group is at war with Iran-backed forces in Syria and Iraq.
The Islamic State group has claimed attacks on Iran's parliament and the shrine of Ayatollah Ruhollah Khomeini, which killed at least one person and wounded several others.
The claim was carried by the IS-run Aamaq news agency and circulated among the group's followers over social media.
The Sunni extremist group is at war with Iranian-backed groups in Syria and Iran and views Iran's Shiite majority as apostates deserving of death.
Iranian media says several attackers, including suicide bombers, took part in the assaults on both sites, with the parliament attack still underway. Lawmakers were in session at the time of the attack, and have been ordered to remain in place.
Iranian state TV says one of the attackers taking part in an assault on parliament has blown himself up.
It says four attackers launched Wednesday's assault on parliament, which has wounded at least eight people. Police have surrounded the building, where a legislative session was underway, and heavy gunfire could be heard from outside.
A separate assault at the shrine of Ayatollah Ruhollah Khomeini, in another part of Tehran, killed a security guard and wounded four other people. It was not immediately clear who was behind the attacks or if they were coordinated.
Iran's state TV says four attackers were involved in a parliament shooting that is still underway, and that eight people have been wounded.
The state TV report did not provide further details, or say whether the shooting was linked to another attack Wednesday on the shrine of Ayatollah Ruhollah Khomeini. There, four attackers, including a suicide bomber, killed a security guard and wounded four other people.
State TV said one of the attackers was killed by security guards and that a woman was arrested following the shrine attack.
Iran's state TV news website says four "terrorists," including a suicide bomber, have attacked the shrine of the late leader Ayatollah Ruhollah Khomeini in the capital, Tehran, killing a security guard and wounding four people.
State TV said one of the attackers was killed by security guards and that a woman was arrested following Wednesday's attack.
Iranian media earlier reported a shooting inside the parliament building that wounded a security guard, without providing further details. It was not immediately clear if the attacks were related.
Iranian media says a man has opened fire inside the parliament building, wounding a security guard in an attack that is still underway.
The semi-official Tasnim news agency says medics are treating the guard. It did not provide further details about Wednesday's shooting.