Tehran - Iranian Foreign Minister Mohammad Javad Zarif condemned twin bomb attacks by the Islamic State group that ripped through crowds of minority Shi'ite Hazaras in the Afghan capital, killing at least 80."Afghanistan terror bombings another instance of depth of Daesh depravity: Shia and Sunni are both victims & must unite to defeat extremists," Zarif tweeted on Saturday, using another name for IS.Foreign ministry spokesperson Bahram Ghasemi added that "eradicating this unfortunate phenomenon (IS) wouldn't be possible without a joint co-operation and understanding among all countries".IS claimed responsibility for the Saturday blasts, which hit during a huge protest in Kabul, the deadliest attacks there since 2001.The first major IS assault on Kabul was apparently aimed at sowing sectarian discord in a country known for relative Shia-Sunni harmony.Iran, a country with a large Shi'ite majority, has a long border with Afghanistan, where the minority Hazara Shi'ites were bombed on Saturday.Day of mourning Afghan President Ashraf Ghani vowed "revenge" against the perpetrators of the attack and announced Sunday as a national day of mourning."This heinous attack was made all the more despicable by the fact that it targeted a peaceful demonstration," the White House said in a statement.Amnesty International said: "The horrific attack on a group of peaceful protestors in Kabul demonstrates the utter disregard that armed groups have for human life."Such attacks are a reminder that the conflict in Afghanistan is not winding down, as some believe, but escalating, with consequences for the human rights situation in the country that should alarm us all."The government has announced a ban on public protests for at least 10 days after Saturday's demonstration, which was largely peaceful before the explosions tore through the crowds.