The Cairo meeting by representatives of the United Nations, European Union, Arab League and African Union came a day after gunmen opened fire at demo nstrators protesting against militias in Libya's capital.
Speaking at a press conference afterwards, Arab League chief Ahmed Abul Gheit said the quartet had followed the "dangerous developments in Tripoli."
"We agreed on supporting the (UN-backed) presidential council in its efforts to exert security control in the capital, including the implementation of the truce agreement," Abul Gheit said.
EU foreign policy chief Federica Mogherini, UN envoy Martin Kobler and African Union Libya envoy Jakaya Kikwete also attended the meeting.
Friday's protests followed four days of clashes between pro-unity government forces and rival militias.
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Kobler said it would not be time to lift an arms embargo on Libya until its armed forces had a clear chain of command.
"If you have an army with a clear chain of command, reporting to the supreme command of the army and the presidency council, they are entitled to exemptions from the weapons embargo," he said.
The fighting in Tripoli lasted four days and subsided only after the GNA signed a ceasefire agreement with militias from Tripoli and third city Misrata, along with local mayors.
The truce announced Thursday has largely held despite brief clashes the same day in the south of the city.
Militias have been key power brokers in a country plagued by violence and lawlessness since the NATO-backed ouster of longtime dictator Moamer Kadhafi in 2011.
The embattled GNA has secured the support of several armed groups, but dozens of militias continue to operate in Tripoli.
Abul Gheit said the quartet that met in Cairo was "prepared to support and facilitate any mechanism for dialogue between the Libyan parties."