The US and the African Union have imposed sanctions against the military leader of Guinea, Capt Moussa Dadis Camara, and 41 members of his junta.
The moves come one day after the UN created a tribunal to probe the killing of at least 150 people when troops fired on an anti-government protest.
Guinean officials say 57 people died and that most were trampled to death.
The US and AU placed travel bans on members of Guinea's junta. The AU also froze the individuals' bank accounts.
The sanctions are the latest punitive measures taken against the junta, which include arms embargoes and travel restrictions imposed by the European Union and West African alliance Ecowas.
The EU has called for Capt Camara to be tried for crimes against humanity, while the African Union has already called for him to step down.
Human rights groups say soldiers raped and sexually abused women during the crackdown in the capital, Conakry, on 28 September.
The rally was called to protest over reports that Capt Camara was planning to stand in presidential elections next year.
After seizing power in December 2008 following the death of long-time leader Lansana Conte, he pledged not to contest elections but has since made a series of contradictory statements about his intentions.