Iran on Saturday blamed Israel for a strike on Damascus, saying it "reserves the right to respond" after the Islamic Revolutionary Guard Corps confirmed four of its members had died.
Foreign ministry spokesman Nasser Kanani decried "frequent violations of Syria's sovereignty and territorial integrity and an escalation in aggressive and provocative attacks" by Tehran's arch-foe Israel.
"The Islamic Republic of Iran reserves the right to respond... at the appropriate time and place" to the latest strike on the Syrian capital, Kanani said.
The Syrian Observatory for Human Rights war monitor said 10 people were killed in the Israeli strike on the Mazzeh neighbourhood of Damascus.
The Guards' Sepah news agency said the "evil and criminal Zionist regime (Israel)" killed four of its military advisers, while Iran's Mehr news agency reported one of them was the force's spy chief for Syria.
In recent weeks, Israel has been accused of intensifying strikes on senior Iranian and allied figures in Syria and Lebanon -- backers of the Palestinian militant group Hamas -- raising fears the Gaza conflict could expand further throughout the region.
Military actions across the region attributed to Israel "reflect the weakness and desperation" of its forces on the battlefield, Kanani charged.
He called the latest strike "a desperate attempt to spread instability and insecurity in the region".
The raid on Mazzeh came four days after the Revolutionary Guard said it attacked "an Israeli intelligence headquarters" in Arbil, the capital of Iraq's northern autonomous province of Kurdistan.
Iraqi authorities said the attack killed four civilians and wounded six others.