Russia and China blocked approval of a U.N. Security Council resolution that would have backed an Arab League peace plan for Syria.
The 13-2 vote Saturday in favor of the resolution was stymied by the two permanent members of the Security Council.
Under the resolution, Syrian President Bashar al-Assad would remove his troops from Syrian cities and step down, transferring power to his vice president.
Russia and China have rejected calls for Assad to leave office and vetoed a Security Council resolution on Syria in October.
"The United States is disgusted that a couple of members of this Council continue to prevent us from fulfilling our sole purpose here -- addressing an ever-deepening crisis in Syria and a growing threat to regional peace and security," Susan Rice, the U.S. ambassador to the United Nations, said following the vote.
"The United States has long said that it’s past time that this Council assumed its responsibilities and imposed tough, targeted sanctions and an arms embargo on the Assad regime, as many individual countries have already done," she added.
The veto came on the same day that more than 200 anti-Assad demonstrators reportedly were killed in the Syrian city of Homs.
Israeli Prime Minister Benjamin Netanyahu responded to the massacre in Syria in a statement before the weekly Cabinet meeting on Sunday.
"We have received a reminder about what kind of a neighborhood we live in. We heard the Iranian ruler's remarks about the elimination of Israel. We saw the Syrian army massacre its own people. We have seen bloody events in our region," he said. "Various leaders have no moral compunctions about killing their neighbors and their own people alike."
The American Jewish Committee said in a statement that it "profoundly regrets" the vetoes by China and Russia.
"Tragically, China and Russia, standing alone, have prevented the U.N. Security Council from adopting any significant measures to help protect the Syrian people from their bloodthirsty ruler, Bashar al-Assad," said AJC Executive Director David Harris. "Their vetoes are all the more troubling on a day when hundreds of Syrians in the city of Homs have been massacred by Assad's forces in what is the deadliest day since the uprising began last March."