The striker is in no doubt United's most valuable asset and has been linked with both Derby County and Norwich City during the past eight months.
But McAllister indicated that any prospective bidders would be wasting their time by inquiring about the former non-league forward ahead of the summer transfer deadline which falls on August 31.
McAllister said: "His attitude throughout pre-season was superb and he looks as if he wants to score goals.
"I'd be disappointed if I didn't have people interested in Jermaine but we're trying to get things going at our place and he's one of our better players.
"He's on a lengthy contract and nobody will leave the club unless I want them to go. That's what the chairman's said to me and I trust him."