Foster joined Birmingham from United earlier this week and has become the first player to openly criticise supporters at Old Trafford.
“It is a bit of a distraction when fans are doing the chants at every game,” he said.
“There is quite a lot made of [United’s ownership],” he continued.
“Sometimes too much. The fans are obviously passionate about the club but they need to focus on just supporting the club a bit more and not getting carried away with the technicalities of who is in charge. The Glazers have always put money towards players when needed.”