The Dutchman has been celebrating his first Premier League title this week.
"I spoke to Nigel de Jong a couple of years ago when he was playing for City," Van Persie told MUTV.
"He said in Manchester there were only City fans and United's come from different cities all over the world.
"It sounded a bit weird. I have to adjust him on that now and say it is definitely not true.
"It is at least 50-50, or, after last Monday, maybe it is 80-20."