At least 19 people were killed and 24 others wounded earlier this month by a blast at a madrassa in Aybak, southeast of Mazar-i-Sharif.
Waziri told AFP Tuesday's blast happened around 7:00 am (0230 GMT) near Sayed Abad Square in the city.
He said six people were injured in the blast.
Further details were not immediately available, and there has been no claim of responsibility.