The 15-member council gave its full support to a plan by the new UN envoy Ghassan Salame for legislative and presidential ballots by July next year.
It "strongly urges all Libyans to work together in a spirit of compromise and to engage constructively in the inclusive political process", a declaration said.
Years of political turmoil in Libya have followed the 2011 overthrow of long-time dictator Muammar Gaddafi.
A mass of migrants have made the lawless country their launchpad into Europe, and the United States has carried out air strikes against Islamic State group jihadists in the North African state.
Salame, appointed UN envoy in July, last month outlined his plan under which a new constitution must be put before a referendum, paving the way for elections.
He also announced that a national conference would be held to reintegrate all the country's "ostracised or marginalised" actors.
After a 2015 UN-backed agreement, a unity Government of National Accord (GNA) with Fayez al-Sarraj as prime minister took office in Tripoli last year.
But it has struggled to impose its authority elsewhere, particularly in the far east, where military strongman Khalifa Haftar controls much of the territory and supports a rival parliament.
The Security Council expressed concern "at the deteriorating security, economic and humanitarian situation in Libya", and said it welcomes the UN's commitment to intensify its work on the ground "to help improve the living conditions of all people in Libya, including migrants".
Currently led by France, the council expressed concern over the threat of terrorism and trafficking in humans and illicit goods.
"In this regard, the council reiterates the need for unified and strengthened national security forces, under a unified, civilian government."