Emergency services were called to Holywell Road, Brightside, just before 5.10pm yesterday after a child was involved in a collision with a car.
The youngster was taken to hospital with minor injuries but South Yorkshire Police said following the collision a disturbance broke out in the street and a youth was arrested on suspicion of assault.
No other details have yet been released.
A South Yorkshire Police spokeswoman said: "Police were called to reports of a collision on Holywell Road, Sheffield.
"It is reported that a car was involved in a collision with a seven-year-old child. The child was taken to hospital with minor injuries.
"Following the collision there is said to have been a disturbance in the street which resulted in a juvenile being arrested on suspicion of assault."
Witnesses are urged to call South Yorkshire Police on 101.