Gunmen shot their way into the luxurious Corinthia Hotel in Tripoli on Tuesday, and it wasn't immediately clear whether there were casualties in the attack.
An online group that supports ISIS said online that the attack was carried out in the name of Abu Anas al-Libi.
Al Libi, an alleged al Qaeda operative accused of involvement in the bombing of U.S. embassies in Africa and who was captured by U.S. special forces in Libya, died in a U.S. hospital earlier this month.
The attack began when militants detonated a car bomb in the parking lot of the hotel Tuesday morning.
The five-star hotel is popular among government officials, some of whom reside there.
Read more: CNN