Mousavi sympathized with the Afghan government and nation, particularly the families of victims and strongly condemned such “acts of aggression and inhumane methods”, according to the Foreign Ministry’s official website.
At least eight people were killed after a bomb detonated near university premises in Afghanistan's capital on Friday, officials said.
Wahidullah Mayar, the Health Ministry spokesman, wrote on Twitter that another 33 people were wounded in Friday's explosion.
Reports said the blast took place near Kabul University's southern entrance.
There has been no immediate claim of responsibility for the attack.
The early morning explosion also set two vehicles ablaze, although it was not clear if the attack was carried out by a suicide bomber or a remotely detonated bomb, according to Kabul police spokesman Ferdous Faramarz.
The attack came a day after eleven people were killed and scores more wounded after the Taliban attacked a police headquarters in the southern Afghanistan's Kandahar city.
Taliban spokesman Qari Yousuf Ahmadi on Thursday said the afternoon attack in Afghanistan's second-largest city started with a car bomb, then saw gunmen storm the police compound.
Baheer Ahmadi, the Kandahar governor's spokesman, said in a statement that 11 people were killed in the attack, including nine civilians and two police officers, while another 89 – including women and children – were wounded.
Two Taliban attackers blew themselves up and six others were shot dead by the security forces, officials said
Kandahar is the former seat of the Taliban, who ruled Afghanistan from 1996 until their removal by a US-led coalition in 2001. Since then, Taliban militants have been fighting US and allied forces, demanding the departure of all foreign troops from Afghan soil.