The European Union, African Union, Arab League and United Nations said Libyans must respect the results and avoid violence or intimidation during and after the political process, in a joint statement following a Monday meeting in Cairo.
A new electoral law would likely have to be agreed on and a referendum on a constitution held before national polls could be organised.
This goal has proved elusive under the current proliferation of militias and the self-styled Libyan National Army (LNA), led by strongman Khalifa Hafter.
Speculation about Haftar's condition led the LNA to hold secret meetings to agree on a successor.
Despite this, LNA spokesman Ahmad al-Mismari has repeatedly stated the army commander is in good health.
Libya has been gripped by chaos since a NATO-backed uprising toppled and killed long-time dictator Muammar Gaddafi in 2011, with rival administrations and multiple militias vying for control of the oil-rich country.
Haftar supports a parliament based in the east of the country, while a UN-backed unity government in the capital Tripoli has struggled to assert its authority nationwide.
Last summer, Hafter announced the "total liberation" of Benghazi, after a three-year campaign to seize the city from jihadists who had made it a stronghold following the revolution.
He is accused by his rivals of wanting to establish a new military dictatorship in Libya.