Iran's Supreme Leader Ayatollah Ali Khamenei, centre, leads the Friday prayers at Imam Khomeini Grand Mosque in Tehran. Picture: Office of the Iranian Supreme Leader via AP
Supreme Leader Ayatollah Ali Khamenei said Iran had delivered a "slap to the U.S.'s image as a superpower" in this month's military confrontation, seeking to rally Iranians around an embattled establishment as he led Friday prayers in Tehran for the first time in eight years.

His speech came amid unprecedented international scrutiny over the Islamic Revolutionary Guard's unintentional shooting down of a Ukrainian passenger plane just hours after Iran had fired missiles into Iraqi bases housing American troops without causing fatalities. That attack had been in retaliation for the killing of a top Iranian commander by the US.

"They're hit by strikes in Syria, in Iraq, in Lebanon and in Afghanistan at the hands of the power of resistance, but this strike was greater than all of those, it was a strike on prestige," Khamenei said of the Iranian action in Iraq. US officials, including President Donald Trump, who claimed to be on the side of the Iranian people are "clowns," he said.

Khamenei branded the US "terrorists" for the January 3 killing of General Qassem Soleimani, whom he credited with being the most effective force in defeating Islamic State.

Soleimani was a hero to many Iranians for his leadership of an elite unit of the Guard which orchestrated Iran's military policy overseas, playing a major role in destroying the extremist group's rule in Syria and Iraq. His killing brought the nation together in mourning but that sense of unity was shattered by the downing of the Ukraine International Airlines plane, which killed all 176 people on board. Most of the victims were Iranian citizens or dual nationals.

Khamenei called the jet disaster an "extremely bitter incident" but said public opinion over the tragedy had been manipulated by U.K. and U.S.-based television channels. The top cleric directly instructed the Revolutionary Guard to carry out a full investigation and guarantee that there could never be a repeat.

Once Iranian officials finally accepted responsibility, after days of denials, protests against the government broke out in Tehran and other cities. Just weeks earlier, security forces had crushed some of the biggest and most sustained anti-regime demonstrations in more than a decade. Human rights groups say hundreds of people were killed in that crackdown.

Worshippers chant slogans during Friday prayers as a banner shows Iranian Revolutionary Guard Gen. Qassem Soleimani, left, and Iraqi Shi'a senior militia commander Abu Mahdi al-Muhandis, and a banner which reads in Persian: "Death To America," at Imam Khomeini Grand Mosque in Tehran. Picture: Office of the Iranian Supreme Leader via AP

While Iran's leaders admitted culpability for the jet disaster they have also blamed the U.S. for creating the sense of crisis that preceded it. In the part of his sermon conducted in Arabic, Khamenei said the "real punishment" for the U.S. would be its forced ouster from the Middle East.

Under pressure from Democrats at home, Trump has offered various justifications for the decision to kill Soleimani, including intelligence that he said pointed to imminent attacks on U.S. embassies, as well as past American military deaths due to Iranian actions supervised by Soleimani in Iraq.

A report on Friday said that nearly a dozen U.S. troops were treated for concussion after Iran's missile attacks in Iraq. The U.S. and Iran have since both signaled they want to back away from further military conflict, but with the two arch foes locked in a deepening confrontation over Iran's nuclear program and American sanctions, tensions in the Gulf remain high.

On Tuesday the U.K., Germany and France angered Tehran by announcing they would activate a dispute resolution mechanism contained in the 2015 nuclear deal which Trump exited before reimposing sanctions. The European move nudged the accord closer to the brink of collapse.

Khamenei accused the European countries of working with the U.S. to try and force Iran "to its knees," and said he had "never trusted them since day one."

Bloomberg