In a live television broadcast on Saturday night, President Ashraf Ghani addressed the nation following the deadly Daesh suicide bombing in Kabul city earlier in the day - which claimed the lives of at least 80 people.
Ghani condemned the attack that also claimed the life of at least one journalist.
He said: "I will get revenge on those who shed the blood of our citizens."
Ghani said it was a tragic day and he ordered Sunday be a day of national mourning.
He said: "Our enemies, by attacking civil liberties, think that they can divide us. But they will fail."
Ghani confirmed that one of three suicide bombers, that had joined demonstrators at the mass rally Saturday, had been gunned down by security forces before he could detonate his explosives.
"I have directed a special commission and the attorney general to investigate the incident and find those responsible," he said.
The Ministry of Interior on Saturday night confirmed the death toll had risen to 80 and that over 230 people were wounded.