Iran on Saturday again threatened retaliation for the deaths of seven Revolutionary Guards in a strike on Damascus, with the army chief saying his country's enemies will "regret" the killings.

Tehran has vowed to avenge Monday's air strike on the Syrian capital it blamed on its arch-enemy Israel, which has not commented.

The attack levelled the Iranian embassy's consular annex in Damascus, killing seven Islamic Revolutionary Guards Corps (IRGC) members including two generals.

Iran's response "will be carried out at the right time, with the necessary precision and planning, and with maximum damage to the enemy so that they regret their action," chief of staff Mohammad Bagheri said on Saturday.

He was speaking at a ceremony in the central city of Isfahan to commemorate Mohammad Reza Zahedi, one of the two dead brigadier generals from the Quds Force, the IRGC's foreign operations arm.

Zahedi, 63, was Quds Force commander for the Palestinian Territories, Syria and Lebanon, according to Britain-based war monitor the Syrian Observatory for Human Rights.

He had held several commands during a career spanning more than 40 years, and was the most senior Iranian soldier killed since a United States missile strike at Baghdad airport in 2020 killed Quds Force chief General Qasem Soleimani.

On Saturday, crowds at the gathering in Isfahan chanted "Down with Israel!" and "Down with the United States!"

The Islamic republic's supreme leader Ayatollah Ali Khamenei has said Israel "will be punished" for the killings.

Monday's strike in Damascus took place against the backdrop of the Gaza war which began with Hamas's October 7 attack on Israel which killed 1,170 people, mostly civilians.

Tehran backs Hamas but has denied any direct involvement in the attack which sparked massive Israeli retaliation against the Gaza Strip.

The Hamas-run health ministry in the Palestinian territory said Friday at least 33,091 people have been killed there during nearly six months of war.

Monday's attack in Damascus, which the Observatory said killed 16 people, was the fifth raid on Syria in a week blamed on Israel.

Tehran does not recognise Israel, and the two countries have fought a shadow war for years.

Iran accuses Israel of having carried out a wave of sabotage attacks and assassinations targeting its nuclear programme.

On Friday, IRGC chief General Hossein Salami warned that Israel "cannot escape the consequences" of the Damascus strike.

Iran arrests three suspected IS group jihadists

Iranian police have arrested three suspected members of the Islamic State group who were plotting attacks at the end of the Muslim holy month of Ramadan, state media reported Saturday.

Those arrested in the city of Karaj in the northwestern province of Alborz included Mohammed Zaker who was identified as "a senior member" of the group, according to the official IRNA news agency.

"The police in Alborz province arrested three members of the Islamic State group who were planning a suicide attack during the end of Ramadan celebrations," IRNA said.

It was not immediately clear when the arrests took place or whether they included foreign nationals.

IRNA also reported the arrest of eight other "accomplices", but without elaborating.

Local media on Tuesday reported the arrest of two alleged IS members in the holy city of Qom.

In January, IS claimed responsibility for twin bombings in the southern Iranian city of Kerman that killed more than 90 people.

The attacks took place at a ceremony commemorating the anniversary of the death of Qasem Soleimani, a top Revolutionary Guards general killed in a US drone strike in Iraq in 2020.

Iran has been battling jihadist and other militant groups for years.

On Saturday, IRNA reported that the number of "martyrs" killed in recent attacks by jihadists near the border with Pakistan had risen to 15, without elaborating.

State media had earlier reported that 10 security personnel and 18 members of the Jaish al-Adl jihadist group were killed in the clashes.

The Sunni Muslim rebel group Jaish al-Adl was formed in 2012 and is listed by both Iran and the United States as a "terrorist" organisation.