ALGIERS, Algeria — The U.S. Embassy in Algiers is warning Americans in the country to avoid non-essential travel amid calls for protests after an attack on a U.S. consulate in Libya.

The embassy said in an emergency message to U.S. citizens that unspecified groups are using online social networks to organize demonstrations in front of the embassy Wednesday "to protest a range of issues."

It warns Americans to avoid large gatherings and non-essential travel in and around the embassy and other official buildings.

The U.S. Ambassador to Libya and three American members of his staff were killed Tuesday night in an attack on the U.S. consulate in the eastern city of Benghazi by protesters angry over a film they see as ridiculing Islam's Prophet Muhammad.