"The timely decision of the Islamic republic regarding its commitments in the (nuclear deal) showed that Iran is not in a position of weakness," said Ali Mottahari, according to the official IRNA news agency.

Tehran announced Wednesday that it would stop respecting some of the curbs on its nuclear activities imposed under the landmark 2015 deal with world powers.

The announcement came exactly a year after the US withdrew from the deal, known as the Joint Comprehensive Plan of Action (JCPOA), with further measures threatened if the agreement's other signatories fail to mitigate the impact of renewed American sanctions within 60 days.

The sweeping sanctions have dealt a severe blow to the Iranian economy.

Mottahari's comments came a day after President Hassan Rouhani called for unity among Iranian political factions during a time of heightened tensions with the United States.

Rouhani said Iran was facing "an all-out war unprecedented in the history of the Islamic republic".

Iran's situation could be worse than during the 1980-1988 Iran-Iraq war, he said according to the government's official website.

"In the war we didn't have any banking, sales of oil and import-export problems and the only sanctions against us were arms embargoes," he said, during what was billed as an informal meeting with members of different political groups and parties.

The administration of US President Donald Trump has ratcheted up pressure on Iran in recent days over alleged threats from Tehran.

Washington said on Saturday it was deploying an amphibious assault ship and a Patriot missile battery to bolster an aircraft carrier and B-52 bombers already sent to the Gulf.