French President Emmanuel Macron offered Thursday to be an "honest broker" in talks between the United States and Iran in order to revive a 2015 nuclear deal which was torpedoed by ex-president Donald Trump.

"I will do whatever I can to support any initiative from the US side to re-engage in a demanding dialogue, and I will... try to be an honest broker and a committed broker in this dialogue," Macron told the Atlantic Council think-tank.

The French leader tried repeatedly and unsuccessfully to persuade Trump to respect the 2015 pact, which placed curbs and checks on Tehran's nuclear programme.

Macron argued in favour of new negotiations with Iran that would also place limits on the Islamic republic's ballistic missile programme and which would include Israel and Saudi Arabia.

The latter countries were fiercely opposed to the 2015 deal and supported Trump's decision to pull the United States out.

"We have to find a way to involve in these discussions Saudi Arabia and Israel because they are some of the key partners of the region directly interested by the outcomes with our other friends of the region," Macron said, speaking in English.

It is unclear if Macron's offer to be a "broker" will be welcomed in Washington.

Iranian Foreign Minister Mohammad Javad Zarif had already suggested in an interview this week that the European Union could help "synchronise" actions by both sides in order to build trust and revive the deal. 

Iran insists that the US drop new sanctions imposed by Trump before it will negotiate, but the new administration of Joe Biden has asked Tehran to respect the terms of the 2015 deal before it will act.

Zarif's suggestion to involve the EU received a cool reception in Washington, where a State Department spokesman reiterated US demands on Tuesday.