The stun grenade went off on Saturday night near an overpass on Mecidiyekoy Yolu Road, which runs alongside the D100 highway through the city's busy Sisli district, the state-run Anadolu news agency reported, adding that the lightly injured victims were taken to a nearby hospital.
Police cordoned off the blast site and a chopper hovered above the scene, the report added. No individual or group has yet claimed responsibility for the attack.
Percussion bombs make a loud noise and cause panic but rarely inflict serious damage or injury.
The incident comes less than a month after a huge explosion rocked the city and killed five people, including the perpetrator. Thirty-six others also sustained injuries in the attack, which was carried out on Istiklal Street in the heart of Istanbul.
