Egyptian President Abdel Fattah Al-Sisi called for a United Nations resolution mandating an international coalition to intervene in Libya after its jets bombed Islamic State targets there.
"There is no other choice, taking into account the agreement of the Libyan people and government and that they call on us to act," he told France's Europe 1 radio in an interview aired on Tuesday.
Asked if it would recommence its own action: "We need to do it again, and all of us together."
Islamic State released a video on Sunday showing the beheading of 21 Egyptian Christians, drawing Cairo directly into the conflict across its border and raising concerns the Islamist insurgents, already active in Syria and Iraq, were spreading their influence further.
Referring to the 2011 Libyan war in which France was part of an international coalition backing forces that deposed former leader Muammar Gaddafi, Sisi called it an "unfinished mission".
"We abandoned the Libyan people as prisoners to extremist militias," he said.
Sisi called on militias to hand in their arms but urged weapons to be supplied to Libya's internationally recognized government, based in the eastern city of Tobruk after rivals seized power in Tripoli.
The Tobruk government has already asked for the lifting of an international arms embargo to help it take back control of the country.
