"The bomb blast targeted vehicles of First Vice-President Amrullah Saleh. Some last vehicles of the convoy have been affected," Arian News TV reported.
An Interior Ministry official told Xinhua that two people were killed and 12 others wounded in the attack.
The blast occurred at 7:35 a.m. (GMT 03:05) in Sabiqa Square of Taimani locality, Police District 4 of the city, sending a column of thick smoke into the sky and triggering panic, a witness said earlier in the day.
"The blast also caused destruction in the populated area," he added.
"The nature of the blast seemed to be a suicide car bomb blast. A convoy of a high ranking official was passing by the area, and the motorcade could be the obvious target of the blast," witness Mohammad Nabi said.
Wednesday's explosion came as peace efforts have been underway with the Taliban.
No group has claimed responsibility for the attack yet.