PARIS - Amid mounting tensions between the United States and Iran, French President Emmanuel Macron is assuming an increasingly familiar mantle: as Europe's go-to leader and top interlocutor.

On key international issues ranging from fighting climate change and online extremism, to pushing a Libyan cease-fire and closer European ties, France's 41-year-old leader has not shied from thrusting himself and his country to center stage, with mixed results.

On Wednesday, Macron faced the particularly thorny challenge of ramping down the escalating standoff between Washington and Tehran, and salvaging the sputtering Iran nuclear agreement. In recent days, he has dispatched top diplomatic adviser Emmanuel Bonne to Tehran, spoken by phone with President Donald Trump, and announced France and Iran would explore conditions for resuming dialogue by July 15.

"Amidst growing tensions on #Iran, @EmmanuelMacron only European leader attempting to prevent unmanageable escalation/#JCPOA collapse," Ellie Geranmayeh, European Council on Foreign Relations (ECFR) Iran expert, tweeted this week, referring to the nuclear deal. Macron's diplomacy, she added, might buy time and create a new political dynamism.

But analysts believe the French president and his European counterparts have few strong advantages. Some suggest the Europeans were too slow in responding to weeks of warnings from Iran that it would soon begin breaching the agreement.

Keeping the deal alive?

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Macron's diplomatic overtures came as the U.N. nuclear watchdog held an emergency meeting Wednesday on Iran's recent breaches of central parts of the 2015 nuclear deal. Called for by the United States, which pulled out of the agreement last year, the talks at Vienna-based International Atomic Energy Agency aimed to ramp up international pressure on Tehran, but instead risked underscoring transatlantic differences on the way forward.

Hours before, the Iranian government praised France's role in reducing tensions. "The French ... are part of efforts to keep the nuclear deal alive," Iranian Foreign Ministry spokesman Abbas Mousavi was quoted as saying by Iran's state news agency, IRNA.

For his part, French Foreign Minister Jean-Yves Le Drian nudged action from Tehran and Washington, urging the U.S. to make "needed gestures of appeasement," and faulting Tehran for violating the Iran deal.

"We're in a situation where U.S.-Iran tensions have actually put the Europeans in a bind," said Tara Varma, ECFR's Paris office head. "I think it's Europe's responsibility to make sure Iran agrees again to the deal, and to show a united European face."

For now, European Union signatories to the nuclear deal - France, Britain and Germany - remain adamant they are sticking to an agreement that once seemed to open lucrative new business opportunities. Even before its inking, companies like France's Total and car maker Renault were scouting out the terrain. Air France and British Airways resumed flights to Tehran halted by years of sanctions. But these and other initiatives ground to a halt over fears of renewed U.S. penalties.

So far, European efforts to establish a workaround to those sanctions have not panned out. In late June, they declared operational the latest initiative, known as INSTEX, although it is modestly aimed at protecting only food and medical trade. It's unclear whether any business has signed onto the mechanism.

"They had the ambition, they had the will, and they tried doing something," prominent French-Iranian lawyer Ardavan Amir-Aslani said of the Europeans in a recent interview, adding he believed the Iran nuclear deal was unworkable from the start. "But Iran is in desperate need of foreign investment, of being able to be paid for its oil and gas sales -and this is not the solution."

The Iranians, he added, "basically feel they've been taken for a ride."

Hope Macron 'can do something'

In Brittany, Vajiollah Mahabadi remains hopeful about INSTEX.

"I'm more positive than negative," he said.

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As the French-Iranian project head at the World Trade Center of Rennes, Mahabadi launched a France-Iran club soon after the nuclear deal was struck, to facilitate what the region hoped would become flourishing two-way ties.

Breton food, cosmetics and technology executives paid visits to Iran. Their Iranian counterparts flocked to an annual Rennes trade show.

Mahabadi said Wednesday the few Breton companies still doing business with Iran are keeping a low profile, especially those with subsidiaries in the U.S.

"It's really difficult," he added, noting Asian banks that once facilitated the commerce are no longer doing so. "Each company has to figure out how to trade with Iran, and the transaction costs are high. But there's still interest - Iran is a market of more than 80 million people."

He also believes Macron, and more broadly, Europe, should have responded more quickly to diffuse U.S.-Iranian tensions.

"I hope he'll be able to do something," he said of the French president. "But it's a bit late."

Analyst Varma disagrees.

"I don't think it's too late," she said of the Europeans, "but they need to stay united. It's important not only for Europe as a strategic actor, but also for regional stability."