Talking on talkSPORT, Barton branded such supporters "losers".
He declared: "My belief is if your Dad or your Grandad don't support the team or you're not born in the city then you should support your local team.
"You shouldn't be attaching yourself to Man United if you're from Canada to get success.
"It's going to sound harsh but they're probably losers and they are going 'oh okay this is the way I can win'.
"Support your local team!"