Iran's Parliament Speaker Ali Larijani on Sunday warned of repercussions for the UN's nuclear watchdog if European nations that launched a dispute mechanism against the Islamic Republic act "unfairly".
Britain, France and Germany launched a process last week accusing Iran with failing to observe the terms of the 2015 deal curtailing its nuclear program, after Tehran criticized the bloc of inaction over US sanctions.
The E3 insisted they remained committed to the agreement, which has already been severely undermined by the US exit from it in 2018 and its reimposition of unilateral sanctions on Iran's economy.
"What the three European countries did regarding Iran's nuclear issue... is unfortunate," Larijani said.
"Iran is not amenable to threat. More than a year and so has passed since America's hostile behavior with regard to the nuclear issue, but Europe has merely issued a political statement. The Islamic Republic of Iran has been patient for too long," Larijani said.
"We clearly announce that if Europe, for any reason, uses Article 37 of the nuclear agreement unfairly, then Iran will make a serious decision regarding cooperation with the agency," he said, referring to the International Atomic Energy Agency (IAEA).
"We will not be the first one to initiate this, but we will act according to your actions, so you had better act fairly," Larijani told the Europeans.
Since May 2019, Iran has progressively scaled back some commitments under the agreement in response to the US sanctions and Europe's inability to circumvent them.
President Hassan Rouhani has repeatedly said that Tehran’s nuclear steps were reversible if Iran’s economy was shielded by other parties to the deal from US sanctions.
Iran's latest and final step in January entailed forgoing the limit on the number of machines used to make uranium more potent.
Tehran said earlier this month it would abandon limits on enriching uranium, though it would continue to cooperate with the IAEA, which is policing the nuclear pact.
The 2015 nuclear deal – known as the Joint Comprehensive Plan of Action (JCPOA) – was struck in Vienna by Iran, the E3, the United States as well as China and Russia.
It has a provision that allows a party to claim significant non-compliance by another party before a joint commission.
Articles 36 and 37 of the deal say if the issue is not resolved by the commission, it then goes to an advisory board and eventually to the UN Security Council, which could reimpose sanctions.
Russia and China have said they saw no grounds to trigger the mechanism and Iran has dismissed the step as a “strategic mistake”.
The decision to begin the so-called dispute mechanism process comes as tensions soared between the US and Iran following the January 3 assassination of Lt. Gen. Qassem Soleimani in an American airstrike at Baghdad airport.
"The issue is not Iran's behavior while you have repeatedly castigated the American withdrawal yourselves," said the Parliament speaker.
"One of the European countries' ministers has explicitly stated that the US has threatened if we do not apply the trigger mechanism, it will raise tariffs on car imports by 25 percent," he added.
"It is America's threats that have pushed a powerful European country to a humiliating and unjust" position, said Larijani.
Germany confirmed last week that the United States had been threatening to impose a 25-percent tariff on European cars if the bloc continued to back the nuclear deal.
“This expression or threat, as you will, does exist,” German Defense Minister Annegret Kramp-Karrenbauer told a press conference in London when asked about the report in The Washington Post.
A group of Iranian lawmakers signed a statement on Sunday warning the European powers to “stop their hostile approach” toward Tehran.
“Otherwise we, as representatives of the Iranian nation, will decide whether Iran should remain in the nuclear deal or whether it should continue its cooperation with the IAEA,” the lawmakers said.
AFP, Reuters and Press TV contributed to this story.