The White House on Tuesday said US President Donald Trump was willing to meet Rouhani without preconditions while maintaining its campaign of "maximum pressure" on Iran.

Rouhani has had a series of phone conversations in recent weeks with Macron.

The French leader has been spearheading European efforts to salvage a nuclear deal between Iran and major powers.

The deal known, formally as the Joint Comprehensive Plan of Action (JCPOA), has been at risk of falling apart since Trump unilaterally withdrew from it in May last year and reimposed sanctions on Iran.

"As Iran's government, parliament and people see it, negotiating with the United States is meaningless as long as sanctions are in place," Rouhani told Macron, according to the government's website.

"If agreements with Europe are finalised, we're ready to return to JCPOA commitments, and a meeting between Iran and the 5+1 is only possible when sanctions are lifted," he added.

The nuclear deal was struck in 2015 between Iran and six major powers -- the UN Security Council's permanent members Britain, China, France, Russia and the US, plus Germany.

It gave Iran relief from sanctions in exchange for putting curbs on its nuclear programme.

Twelve months on from the US pullout, Iran began taking steps back from the deal.

It has since increased its enriched uranium stockpile to beyond the deal's 300-kilogramme threshold and boosted its purity above the 3.67-percent limit as well as firing up advanced centrifuges.

Despite the rollback, Rouhani said last week that Tehran and the European powers had been getting closer to an agreement on a way to resolve key issues.

On Wednesday, he told Macron that the steps Iran has taken so far in reducing its commitments were reversible.

"Iran's third step is under the supervision of the International Atomic Energy Agency and also has the potential to be reversed," he said.