The strike was “coordinated” with the UN-backed Government of National Accord (GNA) of Prime Minister Fayez al-Sarraj, the premier’s spokesman Mohamed El Sallak said.
The raid targeted “a meeting of terrorist leaders” in a house in the Ubari region, 1,000 kilometres (620 miles) south of the Libyan capital, Tripoli, Sallak said on his Twitter accound.
He later told AFP he was not immediately able to identify the jihadists targeted in the air strike.
The US African Command confirmed the strike. “At this time, we assess no civilians were killed in this strike,” a statement said, according to Reuters.
The United States has carried out frequent raids on the Islamic State group in southern Libya.
Libya has been gripped by chaos since a NATO-backed uprising toppled and killed dictator Moamer Gaddafi in 2011, with rival administrations and multiple militias vying for control of the oil-rich country.
Militants and people-traffickers have taken advantage of the chaos to gain a foothold in the North African country.
IS has claimed several attacks in Libya, the latest in February when a suicide car bombing against the forces of Libyan strongman Khalifa Haftar killed three militiamen.
Haftar supports an administration in the east of the country, opposed to the Tripoli-based government of Serraj, who has struggled to assert his authority across the country.