A statement issued on Tuesday by the Presidential Council on behalf of Fayez al-Sarraj, the head of the Government of National Accord (GNA), said that the air strike should be treated as a "war crime".
While the statement did not say who was responsible for the deadly bombing, it called for the immediate lifting of more than a year of siege imposed on Derna city to allow humanitarian aid and for those injured to be evacuated for treatment.
"The siege has left many suffering," said the statement, adding that it will not tolerate the killing and intimidation of Libyan citizens.
Derna has been besieged by armed groups loyal to General Khalifa Haftar, the self-styled chief of the Libyan National Army (LNA).
The Mujahideen Shura Council, which is currently in de facto control of Derna, took the city from ISIL in 2015. It is the only city in eastern Libya not controlled by forces of General Haftar.
Family celebration hit
Local residents told Al Jazeera that the bombing, which was carried out on Monday night, hit a family celebration.
Abdel Rahman al-Sewehli from the High Council of State, an advisory body, tweeted that he "strongly condemned the self-styled LNA Gen Command and its local and international allies", a reference to Egypt which supports Haftar.
Haftar, backed by the government based in the eastern city of Tobruk, is an important and divisive player in Libyan politics.
LNA opposes the UN-backed government based in the capital, Tripoli, which controls much of the western part of the country, including Misrata.
A 2015 UN-backed peace deal has failed to unite warring factions.
Source: Al Jazeera News