A driver was punched and kicked after a minor altercation with another motorist.
The victim, a man aged in his 50s, was attacked in Cairo Street, New Basford, shortly after 4.20pm on Tuesday.
Moments earlier he had been involved in a minor dispute with the driver of another car.
Police arrived on scene shortly afterwards and were helped by members of the public to detain a suspect.
A 25-year-old man was arrested on suspicion of assault. He was later released on police bail.
The victim was taken to hospital where he was treated for minor facial injuries.
Sergeant James Hirst, of Nottinghamshire Police, said: “This was a shocking incident of violence in which a man was left needing hospital treatment. This kind of behaviour is entirely unacceptable, and we are currently working to understand what happened.
“Our investigation is continuing and we would like to speak to any remaining witnesses who may have seen the attack unfold.”
Anyone with additional information is asked to call 101 quoting incident 487 of 21 September.
