Tehran [Iran], June 9 (ANI): Iran has slammed United States President Donald Trump's response to Wednesday's twin terror attacks in Tehran as "repugnant" even as the death toll from the ISIS-claimed assaults rose to 16.

"Repugnant WH (White House) statement and Senate sanctions as Iranians counter terror backed by U.S. clients. Iranian people reject such U.S. claims of friendship," Iranian Foreign Minister Javad Zarif tweeted.

President Trump had earlier said, "We grieve and pray for the innocent victims of the terrorist attacks in Iran, and for the Iranian people who are going through such challenging times. We underscore that states that sponsor terrorism risk falling victim to the evil they promote."

Earlier, two terrorist attacks in the Iranian capital of Tehran killed at least 12 people and wounded more than 40 others on Wednesday.

The Islamic State claimed the two-pronged attack - a suicide bomb and gun assault - on the Iranian parliament and the mausoleum of the founder of the Islamic Republic.

The Parliament assault began when four armed assailants, dressed as women, burst into the building complex and attacked the parliament buildings in the morning, reports Tasnim news.

One of the attackers reportedly blew himself up inside as police surrounded the building.

Equipped with AK-47 assault rifles, handguns and suicide vests, the gunmen killed security guards and ordinary people before holding people hostage in the upper floors of the building.

Security forces laid a siege to the parliament for several hours. Three of the gunmen were shot dead in an exchange of gunfire, while the other blew himself up.

According to the Guardian, this the first attack conducted by ISIS inside majority-Shia Iran.

Attacks are highly rare in Tehran and other major Iranian cities, although a Sunni militant group named Jundallah and its splinter group, Ansar al Furqan, have been waging a deadly insurgency, mostly in more remote areas, for almost a decade.

ISIS, which adheres to a puritanical strain of Sunni Islam, considers Shias heretics and has carried out numerous attacks against Shia civilians, in Iraq in particular.

Also, the attack comes against a backdrop of regional tension, with Arab Gulf countries pushing for a more forceful isolation of Iran. The Gulf states earlier this week severed diplomatic relations with their neighbour Qatar over its close relationship with Tehran. (ANI)