The group is the Movement for Unity and Jihad in West Africa and the leaders were identified as Hamad el-Khairy and Agmed El-Tilemsi, a State Department release said.
As a result of the designation, property of the group and the two men subject to U.S. jurisdiction is blocked and U.S. individuals are barred from conducting business with them, the release said.
The group is also listed by the U.N. al-Qaida Sanctions Committee. That listing requires all U.N. members to freeze assets, and institute a travel ban and an arms embargo against the organization.
"The U.N. action demonstrates international resolve in eliminating [the organization's] violent activities in Mali and the surrounding region," the State Department release said.
Since it was formed in September 2011, the Movement for Unity and Jihad in West Africa has been behind violent terrorist attacks and kidnappings in the region, including the April abduction of seven Algerian diplomats in Gao, Mali, officials said.
Three of the diplomats were released but the organization is still holding the others, making demands in exchange for their freedom and threatening to kill them if the demands aren't met.
Khairy and Tilemsi are founding leaders of the organization, officials said.