"We are assessing the results of the operation and will provide additional information as and when appropriate," Pentagon spokesman Steve Warren said in a statement on Sunday.
The statement did not specify if drones or manned aircraft were used in Saturday's operation, Xinhua news agency reported.
The Libyan government has reportedly confirmed that US warplanes launched an airstrike and killed Mokhtar Belmokhtar and several others, who were affiliated with Ansar al-Shariah, an offshoot of Al Qaeda, in the city of Ajdabiya in eastern Libya.
It added that the US attack came after consultation with the Libyan government.
Belmokhtar is responsible for killing at least 35 hostages, including three Americans, in an attack on a gas plant in Algeria in 2013. The US had filed terrorism charges against him for the murders.