It was the first time in two years that the council agreed on a political statement on Syria, which French Deputy Ambassador Alexis Lamek described as "historic."
Venezuela, which has friendly relations with Syria, said it was disassociating itself from parts of the statement calling for a political transition to end the four-year war.
Caracas envoy Rafael Ramirez said the council was setting "a very dangerous precedent" by supporting a transition that he said violated Syria's right to self-determination.
The peace initiative, set to begin in September, would set up four working groups to address safety and protection, counterterrorism, political and legal issues and reconstruction.
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The council demanded that all sides work for a an end to the war by "launching a Syrian-led political process leading to a political transition that meets the legitimate aspirations of the Syrian people."
The transition includes "the establishment of an inclusive transitional governing body with full executive powers, which shall be formed on the basis of mutual consent while ensuring continuity of governmental institutions."
The statement was adopted a day after Syrian government air strikes on a rebel-held town near Damascus killed at least 96 people in one of the bloodiest regime attacks in the war.