One person was injured in at least one explosion on Thursday at a municipal building in Istanbul, media reports said.
The Anatolia news agency reported one explosion outside the building in Uskudar, on Istanbul's Asian side, while the CNN Turk news channel quoted witnesses as saying that several blasts had occurred.
Hand grenades or small bombs designed to make loud noise rather than kill are thought to have been used in the attack, CNN Turk said.
Two people riding a motorbike were seen fleeing the scene, it added.
The wounded man suffered a minor injury to the leg, NTV television reported.
The police sealed off the area and began investigating the incident.
Two bombs blasts, blamed on separatist Kurdish rebels, ripped through a crowded street in the popular neighbourhood of Gungoren, on Istanbul's European side, on July 27, killing 17 people and leaving about 150 others injured.
Eight people accused of belonging to the separatist Kurdistan Workers' Party (PKK) were subsequently arrested in connection with the blasts.
Leftist and Islamist radicals have in the past also carried out bomb attacks in Istanbul, Turkey's biggest city.