The Islamic State group has released a video purportedly showing three of the gunmen who carried out an attack on a military parade that killed 24 people.
The extremist group, which has claimed responsibility for the attack along with an Iranian Arab separatist movement, released the short video on Sunday on its Amaq news agency.
"Amaq has obtained a video of three of the perpetrators of the attack on the city of Ahvaz in southern Iran yesterday," the pro-IS outlet said.
Comment: What the Ahvaz attack means for Iran's domestic and foreign politics
The footage shows three men dressed in military fatigues riding in a car while vowing to inflict "serious casualties" against the Iranian military.
"How are you guys? Thank God for granting us with the blessing of jihad. There is nothing better than this," one of the men in the video says in the colloquial Arabic of the region.
A second man also speaking in Arabic apologises that he will most likely die in an operation and calls on God to accept him into heaven.
"God willing, there will be an massacre carried out against the [Revolutionary] Guards, who are the enemies of God," the third man says in Farsi.
None of the men mention IS in the footage or pledge allegiance to the leader of the jihadist group.
Iran has said four militants were behind the attack on the parade marking the start of the 1980-1988 Iran-Iraq war, spraying the crowd with gunfire.
Iranian authorities have blamed a domestic Arab separatist group and accused the United States, Israel and Gulf Arab monarchies of backing Saturday's attack. On Sunday, the UAE officially denied any involvement.