The airport east of the city of Benghazi has become a major gateway into Libya since Egypt and Tunisia cancelled almost all flights to the capital Tripoli and the west of the country last week, citing security reasons.
The North African nation has descended into anarchy with a weak government unable to control fighters who helped topple strongman Muammar Gaddafi in 2011 but now vie for control of territory and resources.
The unknown attackers used a Grad multiple rocket launcher but did not cause any major damage and Labraq was still operating, airport director Abu Bakr al-Abidi said.
Tunis Air suspended flights to Labraq and Tobruk in the far east on Sunday. It was one of the last foreign airlines still flying to Libya after rival factions turned Tripoli International Airport into a battlefield last month.