Iran warned the U.S., Saudi Arabia, and Israel Monday that Tehran would take revenge for an attack on a military parade in Iran Saturday.

"You have seen our revenge before," Revolutionary Guard acting commander Gen. Hossein Salami said in a speech at the funeral of some victims that was broadcast on state television, Reuters reports. "You will see that our response will be crushing and devastating and you will regret what you have done."

Four gunmen took aim at Iranian leaders during a military parade Saturday, reportedly killing at least 25 people. Half of those killed were members of the Revolutionary Guard.

Arab separatists have claimed credit for the attack. Four of those who took part in it died in the fighting, according to Reuters.

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The Islamic State also said it was responsible for the assault, but the news outlet reports that it offered no clear evidence to support its claim.

Mourners chanted "Death to Israel" and "Death to America" at funerals Monday.

On Sunday, Iranian President Hassan Rouhani accused the U.S. and its allies of supporting the attackers.

U.S. officials have dismissed the charge, pointing to the tumultuous domestic situation in Iran.

"I think the Iranian people have had enough, and that's where all of this is coming from," U.S. Ambassador to the United Nations Nikki Haley Nimrata (Nikki) Haley'The soul' versus 'law and order' Author Ryan Girdusky: RNC worked best when highlighting 'regular people' as opposed to 'standard Republicans' GOP lobbyists pleasantly surprised by Republican convention MORE told CNN's "State of the Union" on Sunday. "[Rouhani] can blame us all he wants, but the thing he's got to do is look in the mirror."

Secretary of State Mike Pompeo Michael (Mike) Richard PompeoTreasury sanctions individuals, groups tied to Russian malign influence activities Navalny released from hospital after suspected poisoning Overnight Defense: Pentagon redirects pandemic funding to defense contractors | US planning for full Afghanistan withdrawal by May | Anti-Trump GOP group puts ads in military papers MORE also criticized an Iranian leader over who the official chose to blame for the attack. Iranian Foreign Minister Mohammad Javad Zarif also blamed the Gulf countries and America.

"The loss of innocent life is tragic, and I wish Zarif would focus on keeping his own people secure rather than causing insecurity around the world," Pompeo told "Fox News Sunday," adding that it is "an enormous mistake" to blame others for internal security issues.

Tensions between the U.S. and Iran have continued to strain after the Trump administration withdrew from the Iran nuclear deal, reimposing sanctions on Iran and crippling its economy.

President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE is expected to discuss Iran with other world leaders at the United Nations this week. Rouhani will also be in attendance.