Participants of the meeting, which included government officials and members of the Afghan High Peace Council, declared the Taliban illegitimate in the eyes of Islam.
Suicide bombers, as well as those who support and train them, are traitors against Islam, according to a newly issued fatwa.
The Afghan government has armed and trained more than 500 local residents to assist police and security forces at mosques and other Shia religious sites.
The imam of the holiest mosque in the world is urging Muslims to embrace their faith's message of peace and love.
Militants killed more than 30 worshippers in two attacks, according to officials. The "Islamic State of Iraq and the Levant" (ISIL) claimed responsibility for one of the attacks.