The U.S. Senate Foreign Relations Committee passed a resolution Wednesday authorizing the "limited and specific use" of military force against Syria.
Western allies have considered some form of military action in response to an August attack on a suburb of Damascus that may have used chemical weapons. U.S. Secretary of State John Kerry said last week Syrian President Bashar Assad authorized the use of chemical weapons in an attack he said left more than 1,000 civilians dead.
Syria's allies say the attack was a rebel ploy to court international favor.
Chinese Foreign Ministry spokesman Hong Lei said Thursday any unilateral military action against Syria would be a violation of international norms. He called on all sides to "remain calm," China's official Xinhua News Agency reports.
U.S. Sen. Bob Corker, R-Tenn., ranking member of the committee, said the measure provides for an "appropriate use of force" to respond to the use of chemical weapons. China said patience was needed while U.N. investigators examine test results taken from the scene last month.
Hong said China condemns the use of chemical weapons. The next step, however, should be decided by the U.N. Security Council, he said.
China is a permanent member of the Security Council, a status that gives it veto power over tabled resolutions.