MOSCOW — The United States and Russia agreed Friday to take steps that could reduce the violence in Syria, but Secretary of State John F. Kerry and Russian Foreign Minister Sergei Lavrov said they will not outline what they are to prevent “spoilers” from disrupting the initiative.

In a late-night news conference following talks that began in the morning and stretched until almost midnight, Kerry and Lavrov said they had agreed to do things that could cut down on civilian casualties and target designated terrorist groups.

Kerry combined a plea for urgency with a vagueness about what is being considered, or already agreed on.

“International efforts have failed the Syrian people for too long,” he said. “After five years of war, the people of Syria don’t want words, they want action, and they want to be able to live in peace.”

Kerry said that while he and Lavrov had focused on steps to try to realize those goals, “We agreed the best way to make it real is to go about quiet business.”

If the unspecified steps were “implemented in good faith,” Kerry said, “It is possible to help restore the cessation of hostilities, significantly reduce the violence and help create the space for a genuine and credible political transition.”

But, Kerry and Lavrov declined to spell out any concrete steps they had agreed on in what Kerry termed a “public, long list.”.

“I am here with confidence that if the things we talked about are implemented, this has a chance to change the situation,” Kerry said.