Armed assailants, dressed as women, attacked the parliament buildings in the morning.
"They have patrons, they have associates in the Middle East and beyond".
Trump tweeted that "states that sponsor terrorism risk falling victim to the evil they promote".
All of the fourteen people injured in the early Thursday acid attack in southern Tehran have been released from the hospital, head of Iran's Emergency Medical Services Pirhossein Koulivand said on Thursday. Tehran has also propped up Iraq's fight against ISIS, advising Baghdad's predominantly Shiite forces and militias in the battle to recapture cities such as Tikrit and Ramadi.
In an outpouring of support against Iran, dozens of countries have condemned Wednesday's attack on the country's parliament and on the mausoleum of the Ayatollah Khomeini.
Iran's state broadcaster said a security guard was killed at the tomb and that one of the attackers was slain by security guards.
In the wake of Wednesday's attacks, Iran's Revolutionary Guard released a statement accusing the Saudis of being complicit in the attacks.
Last month, the Foreign Relations Committee backed the measure despite concerns from former Secretary of State John Kerry and several Democrats that it could nonetheless lead to the unraveling of the nuclear accord negotiated by the Obama administration. Fars news agency issued a report saying that ISIL claimed responsibility for the terror attacks in Tehran.
(AP Photo/Fars News Agency, Omid Vahabzadeh).
All of the attackers were killed: Four at parliament, four at the tomb of Ayatollah Ruhollah Khomeini, officials said. At least 11 people were killed, and one of the attackers blew himself up inside the complex, according to state television.
One man, recovering in a hospital bed, told state TV he was waiting to meet an MP when shooting broke out.
One detonated a suicide vest, while the other was shot dead.
A picture taken on June 7, 2017 shows the main hall of Iranian parliament with lawmakers gathered during the attack which targeted the complex on June 7, 2017.
In a statement after the attacks, the Guards said they "will never allow the blood of innocents to be spilt without revenge".
The statement said Saudi Arabia "constantly supports" terrorists including the Islamic State group, adding that the IS claim of responsibility "reveals (Saudi Arabia's) hand in this barbaric action".
Parliament was in session as the violence unfolded and members were keen to show they were undeterred, continuing with regular business.
Speaker Ali Larijani dismissed the attacks, saying they were a "trivial matter".
"For these two actions to happen... after this meeting means that the United States and Saudi regimes had ordered their stooges to do this", said Mohammad Hossein Nejat, deputy head of the Revolutionary Guards intelligence branch, according to the Fars news agency.