Waving anti-war signs and chanting in the streets, about 100 people came out to march against proposed military action. They believe an attack would increase the killing and destruction in Syria and provoke wider regional conflict.
"I'm out here because I truly feel that the U.S. is not the world police. It's not our responsibility to end somebody else's civil war," said demonstrator Mark Barsana.
A Boeing engineer, Barsana fears the economic impact of going to war.
"Bridges are falling in the river, our infrastructure is falling apart and we want to spend millions of dollars in the Middle East? I think it's wrong," he said.
Saturday's demonstration is part of a nationwide effort. Small crowds of protesters gathered in Time Square and outside the White House to condemn possible U.S. military action in Syria.
The New York City gathering included anti-war activists, anti-Wall Street activists, and also some Syrian expatriates who said they supported the regime of Bashar Assad. Some carried signs saying, "No more wars for corporate profit," and "Cut the Pentagon, not food stamps."
In Washington, dozens of protesters chanted and picketed, saying Congress shouldn't authorize military action.
In Seattle, Joe Colgan came to the march with his wife. They began speaking out against wars in the Middle East after their son was killed while serving in Iraq.
"It's just terrible, the atrocities," Colgan said. "The weapons we have used and the atrocities we have caused just make me sick."
There was also a Saturday prayer vigil in West Seattle in response to the Pope calling for a day of prayer.