The 30 year-old, currently on hiatus from the sport as he sees out his religious duties of Ramadan, was reportedly driving through his home of Bolton when the incident happened.
Khan, travelling with his fellow-boxer brother Haroon, is said to have made a wrong turn angering the car behind him, prompting several men to ram his six-figure personalised Range Rover 4×4.
A police statement confirms Khan was punched, although an observer who saw what went down claims the one-time super-lightweight king scored a knockout of his own.
“We were called to reports of road rage incident/assault,” said Police.
“It appears the person driving has made a wrong turn and this has angered the person behind them and there’s been an altercation.
“The driver of the first car was punched. There were no arrests. Anyone with information should contact us.”
According to The Daily Mail, the witness said: “These guys tried to jump Amir and his brother but they picked on the wrong blokes.
“They parked their car in front of the Range Rover. At least one had a cosh. One slapped Amir and clipped him on the lip but Amir pulled back and knocked him out cold.
“Then five of them went for Amir and Haroon – but they stood their ground and these guys got dropped one by one. They left these men with cuts and bruises but all they were doing was defending their property.”
A similiar incident happened to Khan in Birmingham back in 2012.
No arrests have been made from this latest altercation.
Some time after the incident, Khan attended a chartiy event alongside Hollywood actress and child star Lindsay Lohan.