Afterward, Ms. Rice said: “We have no desire to have difficult relations with anyone in Iran.” She said the United States has been very clear that “we are prepared to change 27 years of policy and engage in a broad range of issues” with Iran if Iran accepts international demands that it suspend its nuclear enrichment program.

Whether American and Iranian officials would meet and talk directly here at all has been one of the major questions surrounding the international conference. On Thursday, Ms. Rice met with her Syrian counterpart, the first high-level diplomatic contact between Washington and Damascus in more than two years. The meetings with Syrian and Iranian officials appeared to signal a significant, if unstated, change in approach for the Bush White House concerning relations in the Middle East, analysts throughout the region said. Washington is asking for help, even from foes it has spurned in the past. Under pressure from its Arab allies, the Bush administration has slowly edged away from its position that direct talks can be conducted only as a reward for what it considers good behavior.

Iranian-American relations have been especially tense lately, with the United States saying that Shiite militias in Iraq have used weaponry from Iran in attacks on American troops, and with the United States pressing Iran to suspend its nuclear enrichment program. The United States has no diplomatic relations with Iran and has sought to isolate and contain the country.

In today’s opening remarks at the conference, Iran’s foreign minister, Mr. Mottaki, did not seem to have changed his country’s position toward the United States.

“The terrorists claim that they are fighting the forces of occupation, while the occupiers justify their presence under the pretext of the war on terror,” he said. “Therefore, this axis of occupation-terrorism is the root of all problems in Iraq.”