The strikes were requested by the UN-backed new Libyan government, Libyan Government of National Accord (GNA) which has been fighting IS in the region of Sirte since May.
Sources say IS had been using violence to impose Sharia law on citizens in the area.
Libya's prime minister Fayez Sarraj said the strikes caused "heavy losses" and it has been reported that IS has lost a stronghold there.
The attack was authorized by USA president Barak Obama and the Pentagon has said, "These actions and those we have taken previously will help deny ISIL [IS] a safe haven in Libya from which it could attack the United States and our allies."
Libyan militia have been fighting IS in the region, but much of its government and military has been divided into competing factions since NATO forces brought down former-Libyan leader Muammar Gaddafi in 2011.
IS arrived in Libya after Gaddafi fell with many of its soldiers coming in from Syria.
to launch - to send off into the air
coastal - at the coast (next to the ocean / water)
strike - a (military) attack
unmanned drone - using a drone and no humans
manned - using humans
requested - asked for
UN-backed - supported and approved by the United Nations
to impose - to force to follow
Sharia law - Islamic law used in legal governing
stronghold - a strong position of power
authorized - allowed by a person of authority
militia - citizen soldiers
competing factions - different groups that are trying to get power
to bring down - to cause the fall from power