Blasts hit two buses in western Kabul on Saturday, killing at least seven people, according to police.
The explosions took place in a neighbourhood dominated by the minority Hazara community where similar attacks on buses earlier this month killed 12 civilians.
Basir Mujahid, Kabul's police spokesman, added that six people had also been wounded in Saturday's blasts.
Violence has been rising as foreign forces withdraw from the country by Sept. 11 and efforts to broker a peace settlement between the Afghan government and insurgent Taliban have slowed.
It was not immediately clear who was behind Saturday's attacks.
The Hazara community has also been the target of a number of attacks from the Islamic State militant group. In May an unclaimed attack on a school in the area left around 80, mostly school girls, dead.