"The United States condemns the Mauritanian military's overthrow of the democratically elected Government of Mauritania and welcomes the statements by the African Union and the European Union condemning the coup," Rice said.
"We call on the military to release President Sidi Mohamed Ould Cheikh Abdallahi and Prime Minister Yahya Ould Ahmed Waghf and to restore the legitimate, constitutional, democratically elected government immediately.
"The United States looks to all of our international partners to condemn this anti-democratic action," she said in a statement.
Troops overthrew Mauritania's president in a military coup on Wednesday after he tried to sack senior army officers accused of being behind a political crisis destabilizing the country.
Abdallahi was arrested after military convoys rolled through the capital Nouakchott and took over the presidential palace and the prime minister's office, apparently without a shot being fired.
The president's whereabouts were unknow