"The first question that they should ask [themselves], What do wars give America? ... Nothing. No political gain, no economic gain, no good reputation. United States' credibility is at ... [an] all-time low. So this war is against the interests of the United States. Why?" Assad said in an exclusive interview with CBS News Sunday.
Assad again called on the United States to release hard evidence that proved a chemical attack was launched within Syria.
Assad said a military strike on Syria would foster the growth of al-Qaida in his country.
"First of all ... this is the war that is going to support al-Qaida and the same people that kill Americans in the [Sept. 11, 2001, terrorist bombings]," Assad said. "The second thing that we all want to tell to the Congress, that they should ask and that what we expect, we expect them to ask this [U.S.] administration about the evidence that they have regarding the chemical story and the allegations that they presented."
Assad later said U.S. President Barack Obama and Secretary of State John Kerry haven't presented evidence that his regime was behind a chemical attack near Damascus Aug. 21 that killed more than 1,400 people.
The Syrian president said he was "disappointed" by Obama's behavior, comparing his foreign policy to that of former President George W. Bush, who decided to invade Iraq after saying intelligence indicated there were weapons of mass destruction there. The reports were proved false.
"We expected this administration [to be] different from Bush's administration," Assad said.
But, he said: "They are operating the same doctrine with different accessories. That's it. We expect if...[this administration is] to be strong to say that 'We don't have evidence, that we have to obey ... the international law, that we have to go back to the Security Council at the United Nations.'"
Assad told CBS News that even if the United States offered evidence he would doubt its veracity,
"We have the precedent of Colin Powell 10 years ago when he showed the evidence; it was false and it was forged," Assad said. "You want me to believe American evidence and don't believe the indication that we have? We live here."
2014: The Year in Music [PHOTOS]