If this claim was true, it would be the first example of Iran using mid-range ballistic missiles, needed to travel the 400-mile distance, since the end of the Iran-Iraq war.
Iran fired six missiles from the western part of the country into eastern Syria targeting what it called "terrorist bases" in Deir ez-Zor.
Iran's Revolutionary Guard launched the missiles against the site in Deir al-Zour, according to the Tasnim news agency. The extremists have been trying to fortify their positions in the Syrian city in the face of a USA -led coalition onslaught on Raqqa, the group's de facto capital. The IS group did not immediately acknowledge the strikes.
Iraqi lawmaker Abdul-Bari Zebari said his country agreed to the missile overflight after coordination with Iran, Russia and Syria.
Iran presented the missile strike as a response to twin IS terror attacks in Iran on June 7 in which 17 people were killed, and Revolutionary Guards officials warned that other assaults on Iran would lead to similar retaliatory attacks.
However, Spokesperson for the US Central Command Colonel John Thomas said Islamic State terrorists were not present in the Ja'Din village and that it was controlled by the Syrian Democratic Forces.
The attack also sends a clear warning signal to Saudi Arabia which has been trying for some time to test Iran's patience.
It's also created to signal to the US that Iran is fighting the Islamic State on its own terms, he added.
USA warplanes buzzed the pro-Assad forces in an attempt to scare them away from the rebels, and contacted the Russian military to defuse the situation. "The coalition does not seek to fight Syrian regime, Russian or pro-regime forces partnered with them, but will not hesitate to defend coalition or partner forces from any threat", the statement read.
The missile also could strike Riyadh, the capital of Saudi Arabia.
Earlier in the day, the IRGC announced that at least 65 Daesh terrorists, including several high-ranking intelligence commanders, were killed in Iran's missile attack.
Activists in Syria said they had no immediate information on damage or casualties from the strikes.
News on Monday that the strike was intended as a message of intimidation towards Tehran's enemies in the region, primarily Saudi Arabia, as well as a test of the new United States administration under Donald Trump.
US President Donald Trump meanwhile accuses Iran of backing terrorism - a charge it denies - and has threatened to tear up a 2015 nuclear deal between Tehran and major powers.
"We follow their actions and we follow their words", he said Monday.
"The Obama administration constantly spun journalists on foreign policy, and that created this idea that if officials aren't talking about something, they're not paying attention", said the source, a veteran foreign policy adviser who is in routine contact with the White House.
Israeli Prime Minister Benjamin Netanyahu appeared to pour cold water on Monday a Wall Street Journal report that the Jewish. "And I have one message to Iran: Do not threaten Israel".