TEHRAN, April 14 (Xinhua) -- Iran's Foreign Ministry on Saturday condemned the joint strike on Syria's military facilities by the United States, Britain and France.

"This invasion is a clear violation of international regulations and undermining Syria's national sovereignty and integrity," the ministry said in a statement.

It said the United States and its allies invaded Syria "without any proof" of the use of chemical weapons. "They are responsible for their adventurism," it said.

The attack was intended to boost the morale of the "terrorist groups" following their defeat by the Syrian Army, it said, referring to rebel forces and the Islamic State terror group.

The ministry said the Syrian people will prevent the plot to change the situation in favor of the terrorist groups.