"We will bring to justice each one of the terrorists", Alawi said, addressing the funeral procession of the martyrs of the terror attack held in Ahvaz on Monday morning. However, some analysts suggested that the scale of the attack merited a response from a senior US figure.
Ethnic Arab separatists and the Islamic State group (IS) have issued competing claims that they carried out the attack, which was the deadliest in Iran in nearly a decade.
The Islamic Revolutionary Guards Corp has been the sword and shield of Shi'ite clerical rule in Iran since its 1979 Islamic Revolution.
Iran's Intelligence Minister, Mahmoud Alavi, said a network of suspects had already been arrested in connection with the attack, the judiciary's news agency Mizan reported. Women and children were also among the dead and wounded, including a 4-year-old little boy who did not survive.
On Monday, thousands of people gathered outside the Sarallah mosque in central Ahvaz for their funerals.
Authorities declared a national day of mourning, and public offices, banks, schools, and universities will remain closed in Khuzestan Province.
Who was behind the attack?
It also said that the attackers had ties to Israeli intelligence Mossad.
He added, "People had also been invited to the ceremony and the terrorists targeted both the people and the armed forces in the deadly attack". But one of the separatist groups, the Ahwazi Democratic Popular Front, has denied any involvement.
The men appear to be dressed in Revolutionary Guards uniforms and talk about the importance of jihad.
The attack on the military parade is likely to give security hardliners like the Guards more political ammunition because they did not endorse the pragmatist Rouhani's pursuit of the nuclear deal with the West, analysts say. However, none of them stated that they were members of IS or pledged allegiance to the group's leader, Abu-Bakr al-Baghdadi - something that is common in such pre-attack videos.
Supreme Leader Ayatollah Ali Khamenei said the attack showed Iran has "a lot of enemies", according to remarks posted on his website, in which he linked the attackers to the U.S., Saudi Arabia and the United Arab Emirates. "Iran will respond swiftly and decisively in defence of Iranian lives".
The Iranian foreign minister summoned the ambassadors of the Netherlands and Denmark and British charge d'affaires on Saturday evening, Iranian foreign ministry spokesman Bahram Qasemi said. You will see that our response will be crushing and devastating and you will regret what you have done, ' deputy IRGC head Hossein Salami said in a speech before the funeral of the victims in Ahvaz, broadcast live on the state television.
The adviser to the Abu Dhabi government seemed to be referring to statements made by Saudi Crown Prince Mohammed bin Salman, warning that Riyadh will take the fight to "inside Iran".