ROME — Secretary of State John Kerry said on Tuesday that members of the American-led coalition fighting the Islamic State had agreed at a meeting here to intensify their efforts to defeat the group, but he ruled out sending United States forces to intervene in Libya, where the Sunni extremists are pressing to claim territory.

The United States and 22 other nations agreed to “a very specific schedule” for backing the formation of a national unity government in Libya, Mr. Kerry said, and discussed contributions that would be needed from each nation to stabilize Iraq and address the humanitarian crisis in Syria.

“Every single country there agreed that each of us has to do more in order to more rapidly and completely defeat Daesh,” Mr. Kerry told reporters as he wrapped up a day of meetings in Rome devoted to planning the next stages of the battle against the group, using an Arabic acronym to refer to it.

But he said President Obama had made clear that he had no appetite for sending American troops into Libya. “The president will never eliminate every option forever, if common sense dictated that the situation changed, or it required him to adjust, but that’s not in his horizon at the moment,” Mr. Kerry said.