Foreign Minister Heiko Maas said in comments to Bild newspaper's Sunday edition that the seizure of a British tanker Friday and the temporary detention of another has made the situation in the Gulf "a lot more serious and dangerous than it has been."
He says "there can be no winners, only losers, in a possible uncontrolled military escalation" and called on Iran's leaders to fulfill "their responsibilities and not continue with this escalation spiral."
Maas says European efforts are focused on keeping diplomatic channels open with "voices of reason" despite the challenges involved. He says: "This is about preventing war."
An Israeli Cabinet minister says Iran knows "who not to mess with" because Israel is the only country in the world that is killing Iranian operatives.
Tzachi Hanegbi spoke to Israel Radio on Sunday after Iran's seizure of a British oil tanker in the Strait of Hormuz. He was referring to Israel's strikes on Iranian targets in Syria.
Israel has long viewed Iran as its greatest threat and has urged Western countries to take stronger measures against Tehran.
Hanegbi, who serves as regional cooperation minister, says Israel has acknowledged just some of its strikes again Iranian targets in Syria.
He says "the Iranians are very limited in their reactions and it's not because they don't have the capabilities, it's because they understand Israel means business."
In an audio recording released by a maritime security risk firm, a British naval officer can be heard saying that the transit of a British-flagged vessel through the Strait of Hormuz must not be impaired under international law, just before it is seized by Iranian forces.
The same recording has an Iranian naval officer telling the Stena Impero to change course, saying: "You obey, you will be safe."
The audio released Sunday by Dryad Global shows how the British navy was unable to prevent the ship's seizure by Iranian forces on Friday.
Iranian officials say the move came in response to Britain's role in seizing an Iranian supertanker loaded with some 2 million barrels of crude weeks earlier.
Friday's incident comes amid heightened tensions between the U.S. and Iran.