Iran's ballistic missile arsenal is one of the largest and most diverse in the region.
"The bigger slap is yet to come", the ex-IRGC leader tweeted.
"Iran's missile attacks on IS was a great measure preventing the USA from opposition", said Syrian Information Minister Mohammad Ramez Tourjman.
Jennifer Cafarella, of the Institute for the Study of War, said the USA strikes are unlikely to deter Assad and his backers.
Iran's attack on Islamic State targets in Syria did not meet its objectives.
The Guard said the strike was "in retaliation" for June 7 attacks in Tehran that killed 17 people in the first IS-claimed operations in the country.
"It is, if you like, help to those terrorists that the USA is fighting against", Mr Ryabkov said. "It did not immediately offer other specifics, other than to say the missiles were launched from Iran".
Even before that battle is over, however, tensions have risen over control of eastern Syria as Iranian-backed militias, including the Lebanese group Hezbollah, have moved to extend their reach toward areas where the US -based fighters are also operating. On Monday, Russia warned the United States that it will treat the US-led coalition planes in Syria, west of the Euphrates, as targets.
Yaari also told The Times of Israel that his sources were "amazed" at the poor performance of the Iranian missiles.
Sharif said on Monday, however, that the missiles were not only aimed at sending a message to IS, but also to Riyadh and Washington.
The Britain-based Syrian Observatory for Human Rights said government forces pushed on Tuesday into some rebel-held areas in Daraa, as well as its western outskirts. Iran's last foreign missile strike is believed to have been carried out in April 2001, targeting an Iranian exile group in Iraq.
He said it took just 11 days for IRGC forces to pinpoint the command and planning posts used to spearhead the Tehran terror attacks, most of which lied in Dayr al-Zawr. "There was no operational need to attack ISIS from within Iranian territory".
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.
Contrary to the prime minister, Defense Minister Avigdor Lieberman said Israel was not anxious by the Iranian strike. When Iran unveiled the Zolfaghar in 2016, it bore a banner printed with a 2013 quote by Khamenei saying that Iran will annihilate the Israeli cities of Tel Aviv and Haifa should Israel attack Iran.
"We have never had a coherent Syrian strategy", said one USA official, speaking on condition of anonymity. The officials spoke on condition of anonymity because they were not authorized to speak to reporters.
"We are following their actions". "I have one message for Iran: Don't threaten Israel", Netanyahu said.
IDF Chief of Staff Gadi Eisenkot also downplayed the significance of the Iranian strike.