The embattled leader, whose country has been ravaged by six years of war, said his firepower had not been affected by the attack ordered by US President Donald Trump, but acknowledged further strikes were possible.
Assad insisted his forces had turned over all their chemical weapons stocks years ago and would never use the banned arms.
The exclusive interview with AFP in Damascus yesterday was his first since a suspected chemical weapons attack that killed dozens of civilians in the rebel-held town of Khan Sheikhun.
"Our impression is that the West, mainly the United States, is hand-in-glove with the terrorists. They fabricated the whole story in order to have a pretext for the attack," added Assad, who has been in power for 17 years.
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At least 87 people, including 31 children, were killed in the alleged attack, according to the Britain-based Syrian Observatory for Human Rights monitor.
But Assad said evidence came only from "a branch of Al- Qaeda," referring to a former jihadist affiliate that is among the groups that control Idlib province, where Khan Sheikhun is located.
But Assad insisted it was "not clear whether it happened or not, because how can you verify a video? You have a lot of fake videos now."
"We don't know whether those dead children were killed in Khan Sheikhun. Were they dead at all?"
He said Khan Sheikhun had no strategic value and was not currently a battle front.
"This story is not convincing by any means."
The Organisation for the Prohibition of Chemical Weapons (OPCW) has begun an investigation into the alleged attack, but Russia yesterday blocked a UN Security Council resolution demanding Syria cooperate with the probe.
He insisted several times that his forces had turned over all chemical weapons stockpiles in 2013, under a deal brokered by Russia to avoid threatened US military action.
"There was no order to make any attack, we don't have any chemical weapons, we gave up our arsenal a few years ago," he said.
"Even if we have them, we wouldn't use them, and we have never used our chemical arsenal in our history."
The Khan Sheikhun incident prompted the first direct US military action against Assad's government since the war began, with 59 cruise missiles hitting the Shayrat airbase three days after the suspected chemical attack.
Assad said more US attacks "could happen anytime, anywhere, not only in Syria."
But he said his forces had not been diminished by the US strike.
"Our firepower, our ability to attack the terrorists hasn't been affected by this strike.