U.S. President George W. Bush has vetoed the bill, which would have required a troop pullout from Iraq to begin this year.
Osama bin Laden's top lieutenant in the terrorist network Al-Qaeda, al-Zawahiri said that he hoped U.S. forces would stay in Iraq long enough to be dealt a catastrophic blow.
Ayman al-Zawahiri made the comment in a video aired on May 5, four days after Bush vetoed the $124 billion congressional war-spending measure that would have required a troop pullout from Iraq to begin by October 1.
In the video, al-Zawahiri reacts to the legislation passed by the U.S. Congress in late April.
"This bill reflects American failure and frustration," he said. "However, this bill will deprive us of the opportunity to destroy the American forces which we have caught in a historic trap. We ask Allah that they only get out if it after losing 200,000 to 300,000 killed, in order that we give those who spill blood in Washington and Europe an unforgettable lesson which will motivate them to review their entire doctrinal and moral system which produced their historic criminal crusader-Zionist entity."
More than 3,000 U.S. service personnel have been killed in action in Iraq since the U.S.-led invasion in 2003.
Summit Called Successful
A White House spokesman declined to comment on the video, which came two days after a conference on Iraq's future ended in Egypt's Red Sea resort of Sharm el-Sheikh.
UN Secretary-General Ban Ki-moon declared the event a success, noting that many participants promised to forgive much of Iraq's prewar debt, estimated at up to $60 billion.
"I'm very much encouraged by the successful outcome of the two-day meeting on Iraq," Ban said. "The first meeting on the International Compact with Iraq was a great success."
In Iraq today, police say a car bomb killed at least three dozen people and wounded scores of others in a commercial district in a Shi'ite neighborhood of Baghdad.
On May 5, the U.S. military said 33 suspected insurgents had been arrested during house-to-house searches in Al-Latifiyah, 30 kilometers south of the capital. The suspects were reportedly captured late last month.