It said the attack targeted "a command base. of the terrorists in Deir Ezzor", using a different version of the name for the province in eastern Syria.
It did not immediately offer other specifics, other than to say the missiles were launched from Iran.
Iran is allied with Syrian President Bashar al-Assad in the ongoing Syrian civil war. Social media was awash with shaky mobile phone footage from those areas, allegedly showing the missiles rise in an orange glow before heading toward their targets. Iran's Revolutionary Guard, a hard-line paramilitary force, has seen advisers and fighters killed in the conflict.
"The spilling of any innocent blood will not go unanswered", Press TV cited a statement by the Revolutionary Guards as saying.
ISIL, which stands for Islamic State of Iraq and the Levant, and is also known as ISIS, claimed responsibility for the June 7 attacks on Iran's parliament and the Mausoleum of Ayatollah Khomeini that left 17 people dead.
The IRGC said the missile strikes were a warning to deter future Islamic State attacks.
Iran has described the attackers as being "long affiliated with the Wahhabi", an ultraconservative form of Sunni Islam practiced in Saudi Arabia.