File photo. Photograph:( AFP )
Terming Soleimani's death 'great loss', the council described the slain commander as a 'glorious general' who was the "pride not only for Iranians but all Muslims and downtrodden... across the world".
After Iran's top military commander was killed in the US strike in Baghdad, Iran's top security body vowed to avenge the killing at the "right place and time".
"America should know that its criminal attack on General Soleimani has been the country's biggest mistake in west Asia, and America will not avoid the consequences of this wrong calculation easily," the Supreme National Security Council said in a statement.
"These criminals will face severe vengeance... in the right place and time," it added after holding an extraordinary meeting following Soleimani's death.
Terming Soleimani's death "great loss", the council described the slain commander as a "glorious general" who was the "pride not only for Iranians but all Muslims and downtrodden... across the world".
The Security Council also said that the United States would "be responsible for the consequences of all aspects of this criminal adventure".
It said it believes that "the blood of this great martyr... will have many blessings for the great nation of Iran and other freedom-seekers of the world."
The United States on Friday killed Qasem Soleimani, the commander of the Iranian Quds Force, in a strike on Baghdad's international airport.
Watch: Killing of Qasem Soleimani can have repercussions on west Asia and US foreign policy
While the assassination was praised by US President Donald Trump's Republican party members, there were warnings of the danger by various world leaders and urged for restraint.
Iranian President Hassan Rouhani vowed to take revenge as he said that "Soleimani's martyrdom redoubled the determination to stand against America's bullying and defend Islamic values".
Meanwhile, Iran's supreme leader Ayatollah Ali Khamenei said later that Soleimani's deputy in the Guards' Quds Force, Esmail Qaani, would replace the slain commander.
Meanwhile, thousands of people in Iran took streets to protest against Soleimani's killing
Chanting "Death to America" and holding up posters of the slain commander, the demonstrators filled streets for several blocks in central Tehran after Friday prayers.