Ant McPartlin and his mother Christine were assaulted by a teenage gang after the TV star confronted them for filming him on their mobile phones.
The presenter was apparently held in a headlock when he asked the group to leave.
He had been enjoying a meal at the Old Station House in Chiswick with his mother when the gang started making lewd gestures at him and videoing his reaction through the window of the restaurant.
His mother, 58, went outside to intervene, only to be pushed to the ground.
“The youths were banging on the window, filming them and generally just being a pain - and they just wouldn't let it lie,” a witness told The Sun.
“Ant was completely reasonable and said, ‘Leave it out, lads, I’m just having a quiet meal.’
“But it immediately turned really nasty and one of them jumped on him and put him in a head-lock.”
A Metropolitan Police spokesman has since confirmed that there was an incident on Spencer Road in Chiswick on Thursday 13 March.
“No allegation was made and no one suffered any notable injuries,” they added.
It isn’t the first time McPartlin’s fame has caused him trouble. The Saturday Night Takeaway star was reportedly punched in the face in an unprovoked attack in 2011. He was watching football in the Barley Mow in Chiswick when he was assaulted by a teenager.
A representative for McPartlin is yet to comment on the reports.