The two killers were on a motorbike when they shot Colonel Hassan Sayyad Khodayi in his car outside his home in Tehran.
No party has yet claimed responsibility for the second liquidation operation since the assassination of the prominent Iranian nuclear scientist, Mohsen Fakhrizadeh in late 2020.
The Revolutionary Guards described Khodaye's killing as a "terrorist act", blaming it on elements "linked to global arrogance," which may represent a reference to the United States and its allies.
The Revolutionary Guards said, in a statement posted on their website, that Khodaei was "assassinated in an armed attack carried out by two motorcyclists on Mujahideen Islam Street in Tehran" outside his home.
The news was quoted by Iranian media
The official Iranian news agency said that Khodaei was killed by five bullets as he was returning home around 4 p.m. local time (11:30 a.m. GMT).
The agency published pictures showing a man lying in the driver's seat of a white car, with blood appearing around his blue shirt collar and right arm.
From the photo it appears that the shooting came through the window from the front passenger side.
The Revolutionary Guards said that it had opened an investigation to identify the "aggressor," and the Fars news agency reported that the Public Prosecutor visited the crime scene and ordered "the quick identification and arrest of the perpetrators of this criminal act."
The Revolutionary Guards described Khadayi as a "defender of the shrines," a term usually used to refer to anyone working for the Islamic Republic in Syria or Iraq.
Iranian state television said that Khodaye was known in Syria, without giving further details.