Goalkeeper Foster this week secured a £6million move from United to Birmingham, and the 27-year-old's remarks are likely to stir up anger in the supporters he is leaving behind at Old Trafford.
The Red Knights group of wealthy United supporters have recently promised to attempt to oust the Glazers from the club, which is carrying debts in excess of £700million.
Led by leading investment banker and former United director Jim O'Neill, the Red Knights have been inching towards lodging a formal bid for the Old Trafford outfit, which had been anticipated prior to the World Cup's opening game on June 11.
However Foster believes the club is functioning well and suggests fans could make a greater contribution by diverting their energies.
He told morning newspapers: "There's maybe too much made of it by the supporters. They are obviously passionate about Manchester United, 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 in to Manchester United to buy players when needed. Having said that, I don't think the manager needs to buy too many players there anyway. They have a lot of good youngsters coming through the ranks."