A U.N. peacekeeping official in New York said that as of noon ET Thursday, 33 military observers and 27 international civilian staff were in Syria.
A total of 300 are expected to be in the country by the end of the month.
A U.N. official said this week said both sides have violated the cease-fire.
Though the United States seeks an end to all violence, most of the attacks have been by the government forces, said Mark Toner, the U.S. State Department spokesman.
"So far, the Syrian regime has taken, really, almost no steps toward fulfilling the core commitments of the Annan proposal," he said.
Syria's protests started peacefully in March last year, but a government crackdown spawned violence that has left thousands dead and prompted some military defectors to take up arms against the regime forces. The government has consistently blamed the violence on "armed terrorists."
The United Nations estimates that at least 9,000 people have died in the conflict while opposition groups put the death toll at more than 11,000.
President Bashar al-Assad's family has ruled Syria for 42 years.