The U.S. Embassy in Senegal said on Friday it had received information of a bomb threat to the capital Dakar.
In a text message to U.S. citizens, the embassy advised its nationals to stay away from the city centre but did not give any further details.
A Senegalese security source confirmed the threat and said they had taken "necessary measures".
Washington and African governments are backing a six-week-old French military campaign against Islamist rebels in Senegal's neighbour Mali. Senegal has sent several hundred troops to join an African force being deployed to Mali.
The operation is aimed at preventing Mali's desert north becoming a launchpad for attacks in Africa and elsewhere but Islamists have threatened to strike back at anyone who supports the mission.
(Reporting By Ricci Shryock, Diadie Ba; and David Lewis; Writing by John Irish; Editing by Pravin Char)