Iran's foreign minister on Wednesday warned of a tough response from Tehran if President Donald Trump presses ahead with his threats to scuttle the landmark 2015 nuclear deal.
The state-run IRNA news agency reported that the country's top diplomat, Mohammad Javad Zarif, briefed lawmakers during a closed session of parliament on Trump's anticipated refusal to certify Iran's nuclear deal with world powers.
The agency quotes Zarif as saying that if the United States acts against the deal, Iran will offer a "tougher response."
Zarif also told lawmakers that Iran "will never renegotiate" the deal, according to a report on the semi-official Fars news agency.
Trump is expected to decline this week to certify Iran's compliance in the 2015 agreement, referring it to Congress. He also is expected to target the country's paramilitary Revolutionary Guard with new sanctions.
Later Wednesday, Iranian President Hassan Rouhani, told a Cabinet meeting that Trump's speech will make clear "which is the rebellious government, and which is the side that violates international rules."
If the U.S. backs out of the nuclear deal, "it won't be our failure at all, but a failure for the other side," Rouhani said, according to state TV.
Lawmaker Behrouz Nemati warned in comments to IRNA that any new sanctions Trump imposes on the Revolutionary Guard "would mean sanctions against the entire Iranian nation."
In Britain, Prime Minister Theresa May urged the United States on Wednesday to extend the nuclear deal, saying it is "vitally important for regional security."
May's office said she and Trump spoke late Tuesday and both sides agreed their teams would remain in contact ahead of Trump's decision on the pact.
Trump has threatened to scrap the agreement, calling it the "worst deal ever." He must recertify the measure by Oct. 15 because of unilateral conditions set by Congress.
In a rare case of the U.K. publicly pressuring the U.S., the British government said Wednesday that Foreign Secretary Boris Johnson had called Secretary of State Rex Tillerson to underscore British support for the deal.
Johnson said the agreement - under which Iran agreed to limit its nuclear program in exchange for the lifting of economic sanctions - "was the culmination of 13 years of painstaking diplomacy and has increased security, both in the region and in the UK. It is these security implications that we continue to encourage the U.S. to consider."
The Foreign Office said Johnson also spoke to Zarif and will meet Ali Akhbar Salehi, Iran's vice president and head of its nuclear agency, in London on Wednesday.
China, France, Russia, Germany, Britain and the European Union all ratified the deal.
On Tuesday, Salehi warned Washington against undermining the 2015 deal, saying international nonproliferation efforts as well as Washington's international standing would suffer as a result.
Speaking at an international conference on enhancing nuclear safety in Rome, Salehi said that Washington's recent "delusionary negative postures do not augur well" for keeping the deal intact.
He said Iran didn't want to see the deal unravel but that "much more is at stake for the entire international community than the national interests of Iran."
The U.S. administration has faced two 90-day certification deadlines to state whether Iran is meeting the conditions needed to continue enjoying sanctions relief under the deal and has both times backed away from a showdown. But Trump more recently has said he does not expect to certify Iran's compliance with the October deadline looming.