In remarks clearly directed at Trump's 8-month-old administration, Iranian leader Hassan Rouhani told the U.N. General Assembly: "It will be a great pity if this agreement were to be destroyed by rogue newcomers to the world of politics."
"The world will have lost a great opportunity, but such unfortunate behavior will never impede Iran's course of progress and advancement," Rouhani said. As he spoke to the assembly, other nations began signing the first treaty to ban nuclear weapons, a pact spurned by nuclear powers.
Fifty states put their names on the nuclear weapons pact by the end of the day. Guyana, the Vatican and Thailand also have already ratified the treaty, which would take effect if 50 nations take that step.
The U.N. Security Council, meanwhile, approved a resolution supporting efforts to reform the world body's far-flung peacekeeping operations. U.S. Vice President Mike Pence joined the discussion on a Trump administration priority, applauding the resolution and saying all peacekeeping missions should have an exit strategy.
"When a mission succeeds, we must not prolong it. When a mission underperforms, we should restructure it. And when a mission consistently fails to fulfill a mandate of this council, we should end it," he said.
While Iran dominated the second day of the assembly's annual ministerial meeting, plenty of other issues were on the agenda of world leaders. British Prime Minister Theresa May called for stronger steps to rein in North Korean leader Kim Jong Un's nuclear weapons buildup, and Japan's Prime Minister Shinzo Abe urged international unity in pressuring Pyongyang to give up its nuclear weapons.
Palestinian Authority President Mahmoud Abbas warned Israel not to turn the Middle East's decades-long conflict into a religious one. And Ukrainian President Petro Poroshenko renewed calls for a U.N. peacekeeping mission to his country amid what he describes as "blatant" violations of its sovereignty by Russia.
Myanmar's Vice President Henry Van Thio, said his government is committed to long-term solutions to the tensions in Rakhine state, from which more than 420,000 Rohingya Muslims have fled a military crackdown to neighboring Bangladesh.
He spoke at the U.N. late Wednesday in the absence of Aung San Suu Kyi, the leader of Myanmar's civilian government who has been criticized for failing to protect the minority group. The crackdown has been described by the U.N. and others — including Rouhani — as ethnic cleansing. Van Thio said "deep mistrust developed over decades has to be slowly chiseled away."
Rouhani's speech came a day after Trump, in his own address to the assembly, called the U.N.-backed Iran nuclear deal "an embarrassment" to the United States. He also called the Iranian government "a corrupt dictatorship" and "a murderous regime" that funds terrorists.
Rouhani retorted that "the ignorant, absurd and hateful rhetoric, filled with ridiculously baseless allegations, that was uttered before this august body yesterday" didn't befit an organization established to promote peace and respect among nations.
In a later tweet, he made clear that the comments were directed at Trump. Trump hinted that his administration, which has accused Tehran of aiding terrorism in the Middle East, could soon declare Iran out of compliance with the deal. That could unravel it.
Ministers from the seven parties to the agreement met at U.N. headquarters late Wednesday and agreed that all sides are fully implementing the deal, EU foreign policy chief Federica Mogherini said. She said the deal's preservation is important at a critical time in the world.
U.S. Secretary of State Rex Tillerson said Iran is in "technical compliance" with the deal, but he said it's failing to live up to the expectation that the agreement would remove a "serious threat" to the region.
Tillerson said it's a political discussion now about whether to remain in the deal. Rouhani said his country would not be the first to breach the nuclear agreement, "but it will respond decisively to its violation by any party."
He told a news conference later that if the U.S. decides to break the agreement, "any choice and any option" are open for Iran — but he dismissed Trump's "baseless accusation" that the nuclear deal may be providing cover for Iran's eventual construction of nuclear weapons.
"The options that we say we have at our disposal ... will never be going towards nuclear weapons," Rouhani said. "Iran has never sought nuclear weapons, will never seek nuclear weapons, is not now seeking nuclear weapons."
Rouhani repeatedly invoked moderation as Iran's goal and said its missiles — which have been strongly criticized by the Trump administration — "are solely defensive deterrents."
Associated Press writer Alexandra Olson contributed to this report.