Iranian President Hassan Rouhani said the United States wants to create insecurity in the Islamic Republic, a day after an attack on a military parade that killed 25 people. At least eight of the dead served in the Revolutionary Guard, an elite paramilitary unit that answers only to Iran's supreme leader, according to the semi-official Tasnim news agency.
"The attacks are doubtlessly meant to tarnish the prestige of the IRGC, but I believe the terrorist incidents will strengthen the IRGC's standing and even mobilize some public support", said Ali Alfoneh, senior fellow at the Gulf Arab States Institute in Washington.
Fars news agency said the attack lasted about 10 minutes, and appeared to involve four gunmen.
Iran was marking the anniversary of the start of its 1980-88 war with Iraq with military parades across the nation.
It coincided with remarks by Iranian president Hassan Rouhani, who said that United States president Donald Trump will fail in his confrontation with Iran, and vowed Tehran will not abandon its missiles.
In the hours after a suspected terrorist attack on a military parade in the Iranian city of Ahvaz on Saturday left more than two dozen dead, countries from around the world offered their sympathies to the victims.
Saturday's attack comes after a coordinated June 7, 2017 Islamic State group assault on parliament and the shrine of Ayatollah Ruhollah Khomeini, the leader of Iran's 1979 Islamic Revolution.
Iran has ballistic missiles with a range of up to 3,500 kilometres (2,200 miles), enough to reach both Israel and USA bases in the Middle East.
Protests against the government and its handling of the economy that erupted across many provinces late previous year also took place in some cities in Khuzestan, which reported some of the most violent protests.
"On behalf of #PADMAZ organization we reject all accusations and we insist that PADMAZ organization is a civil political movement and has nothing to do with what happen today in #IranMilitaryParade attack", the group said on unconfirmed Twitter and Facebook accounts. He says Iran will respond to the attack in a lawful way.
Yaghub Hur Totsari, a spokesman for a group that identifies themselves as the Arab Struggle Movement for the Liberation of Ahvaz, said the Ahvaz National Resistance, an umbrella organisation of all armed movements, was behind the attack but did not specify which group. The province has a large ethnic Arab community, many of them Sunni, the Muslim denomination to which IS adheres and which is a minority in Shiite Iran.
All but one of the 25 people killed in the attack have been identified.
Mobile phone footage published by the state-run Islamic Republic News Agency showed members of Iran's IRGC and army forces in dress uniform scrambling to the ground while gunfire erupted around them.
"We will never decrease our defensive capabilities".
The gunmen were trained by two Gulf Arab states and had ties to the United States and Israel, according to Shekarchi. In 2009 more than 40 people, including six Guard commanders, were killed in a suicide attack by Sunni extremists in Iran's Sistan and Baluchistan province.