Iran has vowed to retaliate the killing of several members of its Islamic Revolutionary Guard Corps (IRGC) in Israeli airstrikes on the Syrian capital Damascus.

The Islamic Republic will not let the "crime of the Zionist regime" go unanswered, state radio quoted President Ebrahim Raisi as saying Saturday.

Five members of the IRGC were killed in the attack on Saturday in Damascus, including four "military advisors" and one soldier, according to the elite unit. Two of the advisers were high-ranking intelligence officers.

According to the London-based Syrian Observatory for Human Rights (SOHR), three Syrians, one Lebanese and one Iraqi were also killed.

The Revolutionary Guard identified the highest-ranking casualty as the intelligence officer Sadegh Omidsadeh.

The Iran-based Tasnim news agency reported that at least eight people were killed.

The Israeli military had no comment on the attack and typically does not respond to such accusations.

Together with Russia, Iran is the Syrian government's most important ally. Israel regularly attacks targets in the neighboring country to supposedly prevent Iran from expanding its military influence there with the help of militias. Officially, Iran is only active in Syria in an adviser capacity amid the country's civil war.

The attack hit a four-story building in the al-Mazeh suburb, resulting in the complete destruction of the building, the SOHR said.

There was a meeting of commanders close to Iran in the building, but the identities of the fatalities are not established yet, the Britain-based monitor said earlier.

Al-Mazeh is known to house commanders from the IRGC and Iran-allied Palestinians, it said.

Prior to Raisi's comments, Foreign Ministry spokesperson Nasser Kanaani said, in a statement, that Iran reserves the right to retaliate for the "terrorism of the Zionist regime."

"The blood of these high-ranking martyrs will not be wasted," he said.

The ministry condemned the attack as a violation of Syrian sovereignty. The IRGC recently reacted to the killing of a general and terrorist attacks in Iran by hitting targets in Iraq, Syria and Pakistan.

The security situation in the entire region has been particularly tense since the Oct. 7 Hamas incursion into Israel, which responded with a relentless military offensive in Gaza.

In late December, Iranian Gen. Razi Moussavi, a senior IRGC member, was killed in a Damascus suburb in suspected Israeli airstrikes.