The Guards website announced the death of colonels Farshad Hasounizadeh and Hamid Mukhtarband, who "were martyred in recent days while advising and helping the Syrian resistance army".
The commanders' bodies would be buried in Khouzestan province, southern Iran, it said.
On Tuesday, an Iranian state television reporter working in Syria announced on Instagram the deaths of both men, whom he said were killed Monday, identifying Hasounizadeh as a brigadier general.
Colonel Mukhtarband was formerly a brigade commander in the southern Iranian city of Ahvaz.
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Shiite-dominated Iran is Assad's strongest regional ally, sending military advisers from the Guards and other forces to help him against Sunni Muslim rebels seeking his overthrow.
Lebanon's Shiite militia Hezbollah has done much of the fighting to prop up the Syrian army.
The commander of the Revolutionary Guards' foreign wing, Major General Qassem Soleimani, is said to be heavily involved in guiding military strategy.