The Kremlin said Putin and Macron were both calling for "strict observance" of the hard-fought 2015 agreement, which Trump has threatened to torpedo.

The US leader has a May 12 deadline to decide on whether or not to walk away from the deal, which he has derided as "insane" partly because its restrictions on Iran's nuclear activities begin expiring in 2025.

Macron's office said he and Putin "expressed their common will to preserve the gains from the agreement", which saw Iran agree to freeze its nuclear programme in exchange for the lifting of crippling economic sanctions.

On Sunday, US National Security Advisor John Bolton said Trump had yet to decide whether or not to walk away from the agreement.

The US suspended nuclear-related sanctions after the deal was agreed, but the president has regularly to confirm the waiver.

Major European powers Britain, France and Germany all remain committed to the deal, saying it is the best way to keep Tehran from getting a nuclear bomb.

- 'No alternative' -

But Trump and Israeli Prime Minister Benjamin Netanyahu -- who on Monday announced he was set to speak about a "significant development" on the deal -- have called for it to be altered or scrapped.

Macron has positioned himself as an emissary for European officials seeking a compromise that would keep the deal intact, and has previously suggested an additional deal that extends Iran's nuclear restrictions.

But after a state visit to the US this week, he admitted he had failed to secure any promise from Trump to keep the deal alive.

Russia has said that there was "no alternative" to the agreement and that Iran's position on the issue was paramount, while Iran's President Hassan Rouhani has rejected any suggestion of rewriting the nuclear deal.

Macron's office said that both France and Russia want talks with other UN Security Council members as well as European and Middle Eastern powers about how to keep Iran's nuclear capacities in check after 2025.

They similarly backed international negotiations on the wars in Syria and Yemen, committing to working together "in the coming days and weeks" on this.

Macron "indicated his wish for Russia to play a constructive role in all of these questions to avoid tensions mounting in the region", the statement said, in a nod to increasingly cold relations between Russia and the West.

The French president, who has argued for keeping European communications open with Moscow despite tensions over the war in Syria, is due to visit Russia on May 24 and 25.