The Guardian says his remarks came in response to a question about whether the club's decision to sell him was a reflection of their financial position.
"I wouldn't have thought so, there's a lot made of it, maybe too much," Foster replied. "The fans are obviously passionate about the club but sometimes they need to focus on supporting the club a bit more than getting carried away with the technicalities of who's in charge.
"Personally I think the Glazers have always put money into Manchester United to buy players when needed. I don't think they need to buy too many players there anyway. They have a lot of very good young players coming up through the ranks who could do as good a job as anyone else they could bring in."
Foster was then asked whether he thought the supporter protests against the Glazers were one of the reasons why United failed to win more silverware last season.
"Yes, it's a bit of a distraction when the fans are doing the chants at every game and things like that," he said before appearing to backtrack on his comments: "It's not something the players worry too much about, once you're out on the pitch it's blinkers on and you're concentrating on playing football. I wouldn't have thought it contributed too much to only winning the Carling Cup."