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Mr. Kron noted that France under Mr. Hollande often has appeared more willing than the U.S. to use military force against the Assad regime. Indeed, in the weeks leading up to last year’s chemical weapons agreement that helped avert military strikes, it was Mr. Hollande’s government that most vocally pushed for action in Syria.

Still, Mr. Hollande and Mr. Obama favor a diplomatic end to the conflict rather than military intervention.

But such an outcome appears no closer than it did a few months ago.

“We are not making much progress,” U.N.-Arab League Joint Special Representative Lakhdar Brahimi said Tuesday from Geneva, where peace talks between the Assad government and rebel forces resumed Monday. “We all owe it to the Syrian people to move a little bit faster than we are doing.”

The United Nations also reported that at least 500,000 Syrians are unable to access food, clean water and other aid supplies because of security concerns. Snipers believed to be part of Mr. Assad’s forces have fired on humanitarian convoys in parts of the country.

In addition to Syria, Mr. Obama and Mr. Hollande also attempted to present a unified front on Iran, where the U.S., France and other international partners have secured an agreement under which Iran will roll back parts of its nuclear program in exchange for a gradual easing of international sanctions.

There was a hint of pre-meeting tension when Mr. Kerry and other U.S. officials criticized as “not helpful” a major French trade delegation that descended on Tehran this month in anticipation of deals if and when the sanctions are removed. Israel and other critics of the outreach to Iran have warned that business considerations could trump security concerns in dealing with Iran’s nuclear programs.

Mr. Obama gave a stark warning to Western businesses that prematurely try to cut deals with Iran.

“I can tell you that they do so at their own peril right now because we will come down on them like a ton of bricks with respect to the sanctions that we control,” he said.

Mr. Hollande countered that he did not control the actions of private French trade delegations.

“The president of the republic is not the president of the employers union in France, and he certainly doesn’t wish to be,” he said. “Companies make their decisions when it comes to traveling, but I certainly let them know that sanctions were in force and would remain in force.”