The deputy head of Iran's Revolutionary Guards warned US and Israeli leaders on Monday to expect a "devastating" response from Tehran, accusing them of involvement in an attack on a military parade in the city of Ahvaz.
Speaking at the funeral ceremony, the IRGC's acting commander Gen Hossein Salami vowed revenge against the attack's perpetrators and what he called the "triangle" of Saudi Arabia, Israel and the United States.
"You are responsible for these actions; you will face the repercussions. We warn all of those behind the story, we will take revenge," the general said.
"You have seen our revenge before... you will see that our response will be crushing and devastating and you will regret what you have done," he said in a speech on the state television.
On Monday Iran said they arrested 22 people involved in the attack.
"Some 22 people involved in the attack in Ahvaz have been identified and arrested ... weapons, exclusive material and communication equipment were seized in the house that belonged to the five-member terrorist group that carried out the attack," the Intelligence Ministry said, according to the semi-official Tasnim news agency.
Thousands of people packed the streets of the southwestern city of Ahvaz to mourn the victims of Saturday's assault that killed 25 people, including 12 members of the IRGC.
Many chanted "death to Israel and America".
In Saturday's attack, four assailants fired on a viewing stand in Ahvaz where Iranian officials had gathered to watch an annual event marking the start of the Islamic Republic's 1980-88 war with Iraq.
Arab separatists have claimed the assault. ISIS also claimed responsibility for the attack, but offered no clear evidence it carried it out.
Speaking at the funeral ceremony, Iran's Defence Minister Amir Hatami warned the terrorists to expect the revenge of the Iranian nation.
At Monday's funeral ceremony in Ahvaz, Intelligence Minister Mahmoud Alavai announced that many suspects involved in the attack have been identified and "a majority of them were detained."
"We will punish the terrorists, one by one," he promised the crowd.