The Guard's website, as well as semi-official news agencies, reported the strikes Sunday on Deir el-Zour, Syria.
The Islamic republic of Iran is a key ally of the Syrian regime of President Bashar al-Assad, alongside Russian Federation and the Iran-backed Hezbollah movement of Lebanon.
It did not immediately offer other specifics, other than to say the missiles were launched from Iran. Iran's Revolutionary Guard, a hard-line paramilitary force, has seen advisers and fighters killed in the conflict.More news: Wounded US lawmaker 'in some trouble', Trump says
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"The spilling of any innocent blood will not go unanswered", Press TV cited a statement by the Revolutionary Guards as saying.
The Islamic State launched two coordinated attacks against Iran's Parliament and tomb of Ayatollah Khomeini on June 7 in Tehran.
It was the first such attack in Iran and shocked Iranians who believed the chaos engulfing the rest of the Middle East would not find them in the Shiite-majority nation. However, it stopped short of directly blaming the kingdom for the attack, though many in the country expressed suspicion Iran's regional rival had a hand in the attack.