He added that the mastermind of the operation, who had fled the country, was killed by Iranian security forces with help from friendly intelligence services.
The Iranian government is yet to release the documents which it claims prove USA co-operation with ISIS.
The US has imposed new sanctions on Tehran for its support of "terrorist" groups in the Middle East, ballistic missile tests and human rights abuses.
Wednesday's attacks on Tehran's parliament complex and the shrine of revolutionary leader Ayatollah Ruhollah Khomeini killed 17 people and wounded more than 50. "Wednesday's attacks expose the folly of that strategy".
Saadat says in the aftermath of the attack, it feels different to be Iranian.
They were the first attacks in Iran to have been claimed by the Islamic State group. In 2014, the Democratic Party of Kurdistan Iran, an opposition party, published a report about increasing Islamic State activities in Iranian Kurdistan that singled out Sadeghi as a prominent recruiter who, at times, held sessions in a local mosque. The siege lasted for hours, and one of the attackers blew himself up inside, according to Iran's state TV. Because they haven't buckled under aggression from Saudi Arabia and threats from Israel? At the moment, the Americans are happy to sell as many arms to the Saudis and others as possible but I'm sure Mr Trump is going to keep the nuclear agreement with Iran, which is not only with America but Europe, Russia and China.More news: Theresa May's minority United Kingdom government agrees confidence and supply deal with DUP
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In recent years, Tehran has been heavily involved in conflicts in Syria and Iraq against the Islamic State, but had remained untouched by IS violence around the world.
The attack appears to be inflaming the enmity between the countries.
IS has threatened to step up recruitment within Iran, releasing its first Persian-language video in March in which it threatened to "conquer Iran and restore it to the Sunni Muslim nation as it was before". "They have been angry about Iran's power in the region".
Since Trump took office in January, relations between Washington and Tehran have worsened.
One website, KhabarDena.Ir, on Friday quoted a community leader from Paveh, Mamusta Molla Ghader Ghaderi, as saying that some of the attackers were from Paveh.
Support for the JCPOA was reflected in the welcome given to Rohani's re-election by Federica Mogherini, the European Union's foreign affairs high representative, Russian President Vladimir Putin and Chinese President Xi Jinping.