In a powerful rebuke to Syria’s government, the United Nations General Assembly voted overwhelmingly on Thursday to approve a resolution that condemned President Bashar al-Assad’s unbridled crackdown on an 11-month-old uprising and called for his resignation under an Arab League peace proposal to resolve the conflict.

The 137-12 vote, with 17 abstentions, is a nonbinding action with no power of enforcement at the world body, but it represented a significant humiliation for Mr. Assad, whose government had sought to block the vote and severely criticized the sponsors, which included Syria’s brethren in the Arab League.

Bashar Jaafari, Syria’s ambassador to the United Nations, denounced the resolution as a politically motivated scheme to intervene in Syria by the Western powers and others who “would like to settle accounts with Syria.”

A handful of the other countries that opposed the resolution, notably Russia, China, Iran, Venezuela and North Korea, condemned it as an unwarranted interference in Syria’s internal politics. But the wide range of countries that voted for approval for the resolution, which had more than 70 co-sponsors, signified the deep anger and frustration at the United Nations over its inability to halt a conflict that has left thousands of Syrians dead.