The Taliban, seeking to reimpose strict Islamic rule after their 2001 ouster by US -led forces, denied involvement, but blamed the "American process".
No group has yet claimed responsibility but police suspect Daesh, which has been behind a series of bloody attacks in Kabul since 2016.
Ghafor Aziz, a police district chief, said the blast was caused by a suicide bomber who detonated his explosives near the entrance of a compound in the west of the capital where the Afghan Ulema Council was meeting.
At least 14 people were killed in a suicide bombing on a gathering of Afghanistan's top clerics here on Monday, police said on Monday.
On May 30, gunmen armed with assault rifles and grenade launchers stormed the heavily fortified headquarters of the interior ministry, battling security forces for more than two hours.
Around 2,000 members had gathered for the Loya Jirga, or council of elders, in a traditional Afghan tent erected to host the event.
Afghan security officials say a suicide bomb explosion hit a gathering of the country's top religious body in Kabul, killing at least seven people and wounding nine.
The myriad attacks since 2017 included two of the deadliest in the city since the United States invasion: a truck bomb on May 31, 2017 that killed more than 150 people, and an ambulance bomb on January 27 this year which killed more than 100.
The council appealed on both the Afghan government forces and the Taliban and other militants to halt the fighting and agree on a cease-fire.
Almost half all children in Afghanistan are out of school due to conflict, poverty, child marriage and discrimination against girls, the number rising for the first time since 2002, humanitarian organizations said in a report on Sunday.
"It is illegal according to Islamic laws and it does nothing but shed the blood of Muslims", the statement said.
It also asked Taliban to join the peace process, offered by President Ashraf Ghani "in order to prevent further bloodshed in the country".
The Taliban in April announced the start of their annual spring offensive but in recent years, the insurgent group and also the Islamic State affiliate in the country carry out near-daily attacks through all the seasons.