Clinton told reporters Tuesday that the government of Capt. Moussa "Dadis" Camara should apologize to its people and give up power. Camara seized power hours after longtime dictator Lansana Conte died last December.
A human rights group says 157 people were killed and more than 1,000 wounded when government troops opened fire late last month at people who were protesting against Camara. Witnesses say soldiers raped women in the streets.
Clinton said the United States will take "appropriate actions" against Guinea's government.
She added: "Those who committed those acts should not be given any reason to expect that they will escape justice."