"Using chemical weapons in Syria was merely a pretext for the US aggression," Amoli Larijani said, addressing the judiciary officials in Tehran.
Noting that the Americans, themselves, disarmed Syria of chemical weapons a few years ago, he said, "If there is any doubt about the existence of chemical weapons, a fact-finding commission should be formed to scrutinize the issue instead of violating the international laws and launching unilateral military attack."
On Thursday night, the United States launched 59 Tomahawk cruise missiles at the Syrian military airfield in al-Shayrat, located about 40 kilometers (25 miles) from the city of Homs. US President Donald Trump said the attack was a response to the alleged chemical weapon use in Syria's Idlib on Tuesday, which Washington blames on the Syrian government.
Russia described the attack as an aggression against a sovereign state. Following the US military action, Russia decided to suspend its memorandum of understanding on air safety over Syria with the United States, according to the Russian Foreign Ministry.
Syrian opposition claimed Tuesday Syrian army had used a chemical gas on people in the Northwestern province, killing nearly 80 and injuring 200. Assad argued his government has no chemical weapons after agreeing to have them destroyed in 2013. He also ruled out having used chemicals against own people.
In relevant remarks on Saturday, Iranian President Hassan Rouhani asked for setting up a fact-finding committee to study the recent chemical attack against Khan Sheikhoun region in Syria's Idlib province.
"The (fact-finding) delegation should be formed without the US presence and heading, and it should study who has supplied the chemical weapons used in Syria, and from where," President Rouhani said.
"Based on the UN announcement, the Syrian government has no chemical weapons, therefore, it should be clarified from where these weapons have been brought," he added.
President Rouhani reiterated his call again today in a press conference with the Iranian and foreign reporters in Tehran.
Also, on Sunday, Secretary of Iran's Supreme National Security Council (SNSC) Ali Shamkhani underlined that the result of investigations by a fact-finding committee on the chemical attack in Syria will bring another disgrace for the US which attacked the country before any probe.
"In case an international fact-finding committee is set up and the realities behind the issue (chemical attack against Idlib) are studied, another scandal will be registered in the US record of international security violations," Shamkhani said in a phone conversation with Director of the Syrian National Security Bureau General Ali Mamlouk.
He reiterated Tehran's continued support for the Syrian government and people's fight against terrorists, and said the US missile strike against a Syrian airbase in Homs province was an attempt to boost the terrorists' morale.