Dismayed European allies are seeking to salvage the nuclear pact with Iran after President Donald Trump pulled the United States out of the landmark accord, prompting officials in Tehran to pour scorn on the US leader.
"The deal is not dead. There's an American withdrawal from the deal but the deal is still there," French Foreign Minister Jean-Yves Le Drian said.
French President Emmanuel Macron would speak later on Wednesday to his Iranian counterpart Hassan Rouhani, Le Drian said. Iran also signalled its willingness to talk.
Trump announced on Tuesday he would reimpose US economic sanctions on Iran to undermine what he called "a horrible one-sided deal that should have never, ever been made".
The 2015 agreement, worked out by the United States, five other world powers and Iran, lifted sanctions on Iran in exchange for Tehran limiting its nuclear program.
Trump complained that the deal, made under his predecessor Barack Obama, did not address Iran's ballistic missile program, its nuclear activities beyond 2025 or its role in conflicts in Yemen and Syria.
In response to the US pull-out, oil prices rose more than 2 per cent on Wednesday.
Trump's decision could also strengthen the hand of hardliners at the expense of reformers in Iran's political scene.
France's Le Drian said Iran was honouring its commitments under the accord.
"The region deserves better than further destabilisation provoked by American withdrawal. So we want to adhere to it and see to it that Iran does too, that Iran behaves with restraint," he said.
The European Union said it would remain committed to the deal and would ensure sanctions on Iran remain lifted, as long as Tehran meets its commitments.
The prospects of saving the deal depend in large measure on whether international companies are willing and able to still do business with Iran due to the US sanctions.
In a harbinger of what could be in store, Trump's new ambassador to Germany said German businesses should halt their activities in Iran immediately.
French Finance Minister Bruno Le Maire said Trump's decision was a mistake and that the US should not consider itself the world's "economic policeman".
In Tehran, the speaker of the Iranian parliament mocked Trump, saying he was not fit for his job.
"Trump does not have the mental capacity to deal with issues," speaker Ali Larijani told the assembly.
Members of parliament burned a US flag and a symbolic copy of the Iran deal as a session of parliament began. They also chanted "Death to America".
President Hassan Rouhani, a reformist, struck a more pragmatic tone, saying immediately after Trump's announcement that Iran would remain committed to the deal without Washington.
"If we achieve the deal's goals in cooperation with other members of the deal, it will remain in place," he said in a televised speech.
China said it regretted the US pull-out. Its foreign ministry said Beijing would safeguard the deal and called on all parties "to assume a responsible attitude".
UN inspectors say Iran has not broken the nuclear deal.
Renewing sanctions would make it much harder for Iran to sell its oil abroad or use the international banking system.
Iran's growing military and political power in Yemen, Syria, Lebanon and Iraq worries the US, Israel and US Arab allies such as Saudi Arabia.