French President Nicolas Sarkozy and Barack Obama heaped praise on one another Friday, as they expressed a mutual commitment to fighting the Taliban in Afghanistan and keeping nuclear weapons out of the hands of Iran.

The presidential candidate met with Sarkozy in Paris, where they also discussed Iraq, climate change and other issues.

Afterward at a press conference, Obama said Iran should promptly accept an international call to freeze its uranium enrichment program, which some nations see as a potential step toward obtaining nuclear weapons.

He urged Iran's leaders not to wait for the next U.S. president to pressure them "because the pressure, I think, is only going to build."

Obama said that he and Sarkozy agreed that Iran poses "an extraordinarily grave situation." He said the world must send "a clear message to Iran to end its illicit nuclear program."

Obama also said that "Afghanistan is a war we have to win," and Sarkozy agreed.

"In Afghanistan we are not allowed to fail," the French president said, according to a translation. "We cannot let the Taliban return. ... We stand by our allies there."

He did not endorse Obama, but the two officials exchanged pleasantries.

"Of course it's not up to the French to choose the next president of the United States of America," Sarkozy said. "But I am especially happy to be meeting with the senator."

He recalled their last meeting in 2006 in Washington, and joked: "One of us became president, and let the other do likewise -- that's not meddling."

Obama noted that the only other U.S. senator Sarkozy visited on that trip was John McCain, and quipped: "he seems to have a good nose for how things play out."

Obama called Sarkozy a "rock star" and said, "I can't imagine somebody who better captures the enthusiasm and the energy of France than your president."

Obama is in the midst of a weeklong tour of the Middle East and Europe as the first-term U.S. senator seeks to burnish his international credentials for the general election campaign against McCain. The trip began with a campaign-season tour of the war zones in Iraq and Afghanistan and ends with meetings with old allies France and Britain.

McCain foreign policy adviser Randy Schuenemann released a statement Friday criticizing him for his Iran statements.

"Last month, Barack Obama disparaged European diplomatic efforts with Iran as outsourcing. Today, Barack Obama urged Iran to accept the incentives package proposed by the European Union and avoided any mention of his unconditional Presidential summitry. Barack Obamas inexperience is on global display," he said.

The Associated Press contributed to this report.