WASHINGTON  In a propaganda salvo by Al Qaeda aimed at undercutting the enthusiasm of Muslims worldwide about the American election, Osama bin Laden’s top deputy condemned President-elect Barack Obama as a “house Negro” who would continue a campaign against Islam that Al Qaeda’s leaders said was begun by President Bush.

Appealing to the “weak and oppressed” around the world, the Qaeda deputy, Ayman al-Zawahri, said in a video released Wednesday that the “new face” of America only masked a “heart full of hate.”

For years, the terrorist network sought to fuel anti-Americanism with prolific audio and video recordings vilifying President Bush as the leading American “crusader” against Muslim nations. The election of Mr. Obama, a black man who spent part of his childhood in Indonesia and whose father was from a Muslim family, has muddied Al Qaeda’s message.

The Qaeda leader described the victory by Mr. Obama, who has called for a troop withdrawal from Iraq, as the American people’s “admission of defeat in Iraq.” But he warned Mr. Obama that the United States risked a reprise of the Soviet Union’s failures in Afghanistan if the president-elect followed through on pledges to deploy thousands more troops to Afghanistan to carry on the fight against Al Qaeda and its Taliban allies.