The Villa left-back has suggested the chance to play at a higher level is something that Milner would consider.
A star is born: James Milner has excelled for club and country this season
Manchester City have already had an opening bid of £20million rejected for Milner, who is preparing along with Warnock as part of Fabio Capello's provisional 30-man England squad ahead of the World Cup.
Milner does not know if he will be at Villa next season and he is in demand after an outstanding campaign which saw him chosen as the PFA's Young Player of the Year award winner.
Warnock, speaking after England's 3-1 win over Mexico at Wembley,said: 'I don't think the amount of attention James is getting is asurprise.
'I think everyone knows his ability and what he's about and what he's put in on the pitch at Villa this year.
'Ithink everyone knew his reputation before he even joined Villa, what hecould be and what potential he had about him, and he's done very well.
'He can operate anywhere, he's very comfortable anywhere he plays and he's a quality player.
'I don't think the speculation (about his future) has affected him at all. You only have to see the way he's been in training and the way he played the other night (against Mexico). Nothing bothers him really, he just gets on with it.'
Fearing the worst: Stephen Warnock says a big money move will lure James Milner away from Villa Park
Warnock added: 'Of course, we want him at Villa next season but I think, if the price is right, it's very difficult for a club to turn it down.
'From his point of view, if there's a chance to play at a higher level, then it's something that I'm sure he'll be open to.'
Warnock has confidence in 24-year-old Milner to stay in the England side if he is given chances by Fabio Capello.
Warnock said: 'He's doing well, he's a quality player, we all know how good he is and we know what he can do.
'He's a very good player and he's more than capable of holding down a place in this (England) team.' Milner hints at Man City move: 'I don't know if I'll be at Aston Villa next year'Milner's new highs: Villa star will breathe easy if he makes it into final 23THE MIDLANDER: Milner deserves the chance to double his moneyASTON VILLA FC