The 25-year-old has suitors in the Premier League, according to his agent Jonathan Barnett.
However, the 71-year-old claims that United are not one of those teams, despite their long time admiration for the England attacker.
In an interview with SNTV, Barnett said of Grealish's future: "The truth is we don't know (what will happen).
"There are many clubs (interested) and I wouldn't put Manchester United at the top of that (list).
"But he could stay.
"He could stay as well so it's a conversation the club, Aston Villa, will have with Jack and ourselves then we'll see where we go."
Barnett also said recently on Sky Sports about Grealish: "He loves Villa but I think we just have to wait and see how things pan out.
"At the moment he is a Villa player and he has no thoughts about anything else.
"He could be a big star in the summer, he maybe should have been playing a little bit earlier for England.
"It is unfortunate that he has got this injury at the moment but that will be fine.
"The only hope is he is given a chance and he will be great."
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