"Guard colonels Ehsan Karbalaipour and Morteza Saidnejad were martyred -- a crime committed by the Zionist regime during a rocket attack in the suburbs of Damascus, Syria, yesterday morning," said a statement issued on Sepah News, the Guards' website.
Israel, it said, "will pay for this crime".
Both Iran and Russia have provided financial and military support to President Bashar al-Assad's regime since Syria's conflict began in 2011.
On Monday a war monitor, the British-based Syrian Observatory for Human Rights, said Israeli strikes killed two pro-Iran militiamen and wounded six others.
The target of the strikes was "a weapons and ammunition depot operated by Iran-backed militias near Damascus international airport", it said.
Syrian state media said the Israeli missiles killed two civilians, something the Observatory, which relies on an extensive network of sources inside Syria, said it could not confirm.
Tehran says it has deployed its forces in Syria at the invitation of Damascus and only as advisers.
This is not the first time Iran has accused Israel of killing members of its armed forces in Syria.
In 2018, Tehran said four military "advisers" were killed by an Israeli "aggression" in central Syria. The Guards had also previously announced the death of some of their members "on a mission" in Syria.
Syria's official SANA news agency said Israel carried out Monday's strikes at around 5:00 am (0300 GMT), hitting positions south of the capital.
"Our air defence systems intercepted the missiles, downing most of them," SANA said.
According to the Observatory, Israel has carried out raids in Syria at least seven times so far this year.
Last month, Israeli raids near the capital killed two Syrian soldiers and four Iran-backed militiamen, the Observatory said.
Since civil war broke out in Syria in 2011, Israel has carried out hundreds of air strikes inside the country, targeting government positions as well as allied Iran-backed forces and fighters of Lebanon's Shiite militant movement Hezbollah.
While Israel rarely comments on individual strikes in Syria, it has acknowledged mounting hundreds of them since 2011.
The Israeli military has defended them as necessary to prevent its arch-foe Iran from gaining a foothold on its doorstep.
The conflict in Syria started with the brutal repression of peaceful protests and escalated to pull in foreign powers and global jihadists. It has killed nearly 500,000 people.
