Donald Trump declined to comment when asked whether he was aware of Javad Zarif's presence in Biarritz.

Iran's foreign minister flew in for side talks at the G7 summit on Sunday as host France ramped up efforts to ease tensions between Tehran and Washington, a dramatic diplomatic move that the White House said had surprised U.S. President Donald Trump.

European leaders have struggled to tamp down the brewing confrontation between Iran and the United States since Trump pulled Washington out of Iran's internationally-brokered 2015 nuclear deal and reimposed sanctions on the Iranian economy.

Foreign Minister Mohammad Javad Zarif flew to the southwestern French town of Biarritz where the Group of Seven leaders are meeting, delaying a planned trip to Asia.

If his trip yields any advances to ease the Iran crisis, it would represent a huge coup for French President Emmanuel Macron, although the move is not without risks.

"Zarif came to Paris on Friday with Iranian propositions which obviously must be refined," a French presidency official said.

"Yesterday there was a substantial discussion between G7 leaders and it is important to now update Zarif in order to keep closing the gap ... on the conditions with which we could de-escalate the tensions and create breathing space for negotiations."

Zarif was holding talks with France's Foreign Minister Jean-Yves Le Drian, the official said. French, Iranian and U.S. officials said no meeting was scheduled at this stage with U.S. officials.

Macron spent two hours with Trump over lunch on Saturday and all seven leaders discussed Iran at length in the evening. The French official said the decision to invite Zarif was made after the dinner.

Trump declined to comment when asked whether he was aware of Zarif's presence in Biarritz. A White House official said "it was a surprise" to Trump that Zarif had been invited.

Calling Zarif's visit a parallel event to the summit, German Chancellor Angela Merkel said every opportunity should be seized to reduce tensions and that she had been informed at short notice.

U.S. authorities earlier this month placed Zarif under U.S. sanctions.

"Zarif will convey the Iranian leadership's response to French President Emmanuel Macron's proposal aimed at saving Iran's 2015 nuclear deal," a senior Iranian official told Reuters.

Iran's foreign ministry spokesman said Zarif would return to Tehran on Sunday before heading to China.

Trump had earlier appeared to brush aside French efforts to mediate with Iran, saying that while he was happy for Macron to reach out to Tehran to defuse tensions, he would carry on with his own initiatives.

The 2015 nuclear deal between Iran and major powers aimed to curb Iran's nuclear activities in exchange for the lifting of many international sanctions on Tehran. Since pulling Washington out of the deal last year, Trump has pushed a maximum pressure policy to try to force Iran into a new negotiation that would include its ballistic missile programme and regional activities.

IRAN SEEKS OIL EXPORTS

While Trump's European allies also want new talks with Iran, they believe the nuclear deal must be upheld. Macron, who has taken the lead in Europe in trying to salvage the agreement and avert a deeper crisis in the Middle East, met Zarif in Paris on Friday.

They discussed proposals to de-escalate tensions between Washington and Tehran, including easing some U.S. sanctions or providing Iran with an economic compensation mechanism to make up for oil revenues lost under U.S. sanctions.

In response to the tougher U.S. sanctions and what it says is the failure of European powers party to the deal - France, Britain and Germany - to compensate it for lost revenues, Tehran has responded with a series of moves, including retreating from some of its commitments to limit its nuclear activity.

Highlighting just how difficult it will be ease tensions, two Iranian officials and one diplomat told Reuters on Sunday that Iran wants to export a minimum of 700,000 barrels per day of its oil and ideally up to 1.5 million bpd if the West wants to negotiate with Tehran to save the nuclear deal.

One of the Iranian officials also said Iran's ballistic missile programme was not open for negotiation.

"We'll do our own outreach, but, you know, I can't stop people from talking. If they want to talk, they can talk," Trump said earlier when asked about Macron's mediation efforts.

The United States has made no indication it will ease any curbs and it is unclear what kind of compensation mechanism Macron wants to offer Iran, given at this stage a proposed trade channel for humanitarian and food exchanges with Iran is still not operational.

Macron has also said that in return for any concessions he would expect Iran to comply fully with the nuclear deal and for Iran to engage in new negotiations.

"It's unprecedented and given the context it's pretty audacious," said a French diplomatic source.