"I clearly declare that the US president, the French president and the UK prime minister are criminals and have committed a crime," the Leader said at a meeting which was attended by top government officials and ambassadors of Muslim countries here on Saturday.
The three countries, Ayatollah Khamenei said, "will achieve nothing and make no benefit, as they have been in Iraq, Syria and Afghanistan in the past few years, and committed such crimes but have not profited from them."
US and Russian military officials say more than 100 cruise missiles were fired at Syria during early Saturday airstrikes by the United State, France and Britain.
"Those who were overtly and covertly supporting Daesh claim today to be confronting and defeating them [the terrorists]! That's a lie; that is not the case. They had no role" in efforts to defeat the Takfiri outfit, the Iranian leader said.
The Americans would enter the scene of the battle and help Daesh, Arabic acronym for ISIS whenever the terrorists were under a siege and about to suffer a defeat.
The Iranian leader added that the US created the "evil creatures" called Daesh, using the money provided by the Saudi regime and the likes.
However, Ayatollah Khamenei added, the resistance against the US and its agents saved the Iraqi and Syrian nations.
Ayatollah Khamenei also referred to comments by US President Donald Trump, who said last month that his country spent seven trillion dollars in the Middle East and still "got nothing."
Trump "is right," Ayatollah said. "They achieved nothing, and the US will not achieve anything in the future either no matter how much money it spends."
Meanwhile Iranian President Hassan Rouhani said that the US aggression in the region "will have no result but annihilation and destruction," adding that the aggressors "seek to justify their presence in the region through these attacks."
The aggressors are angry about the defeats of the terrorists they supported in Syria's Eastern Ghouta region, he pointed out, stressing, however, that the Syrian people will keep up their resistance.
IRGC warns US of fallout
The Islamic Revolution Guards Corps (IRGC) said that the tripartite attack on Syria will fail to weaken the resistance front, but rather reinforce it in the face of interventionist measures.
"The Americans should wait for the consequences of their moves," IRGC Commander Brigadier General Yadollah Javani told Fars news agency.
They "imagine they can change the situation on the ground in Syria with such measures, but it will not happen definitely," he added.