WASHINGTON—The Obama administration shut the U.S. embassy in Syria Monday due to rising violence in the country that U.S. officials said placed American diplomats in Damascus at increasing risk.

The State Department said it had repeatedly requested additional security from President Bashar al-Assad's government but was rebuffed.

U.S. Ambassador to Syria, Robert Ford, will maintain his position based out of Washington, but will focus on working with Syria's political opposition to ensure an eventual political transition inside the Arab country, the State Department said.