The driver stopped in the Repco carpark, when the man in the motor-home exited his vehicle, walked up to the man's car and began filming with his cellphone, while remonstrating with the man.
The motor-home driver then punched the man in the face, and the victim backed off, not wanting a fight, he said.
"I don't retaliate these days, it wouldn't be a good fight.''
He did not appear to have been injured.
After this, the motor-home driver fled the scene as police were called.
While two officers were interviewing the driver and a witness, the motor-home returned to the scene, and the alleged assailant began speaking to police.
A police spokeswoman said the driver of the motor-home was spoken to by police and warned for threatening behaviour.