A suicide bomber killed at least eight people on Monday near Muslim clerics leaving a giant tent in the Afghan capital.
Reports from security officials indicate that they had gathered to denounce terrorism and call for peace.
No group immediately claimed responsibility for the attack. A series of bombings in Kabul has killed dozens of people in recent months and has shown no sign of easing during the Muslim holy month of Ramadan.
Islamic State (IS) has claimed many attacks in Kabul but security officials say several are much more likely to be the work of the Haqqani network, affiliated with the Taliban
The terror group is seeking to re-impose strict Islamic rule after their 2001 ouster by US-backed forces.