The blast occurred at a mosque in Police District 5 when worshippers were holding Friday prayers at midday, Kabul police spokesman Khalid Zadran wrote on social media.
"The initial reports found three people were wounded. The security personnel arrived at the scene and an investigation was underway," he said.
"We heard a blast when people were offering Friday prayers in Ayoub-e-Sabir Mosque in Char Rahi Qambar locality. The whole place has now been sealed off," an eyewitness told Xinhua.
The Taliban security forces cordoned off the area shortly after the blast, keeping people from gathering, he said.
No group has claimed responsibility for the attack.
In recent months, the war-torn country was hit by a series of terror attacks reportedly staged by militants of the Islamic State terror group.