It was claimed on Sunday that United had struck an £80m agreement with Leicester to take Maguire to Old Trafford.
Asked if United had signed Maguire at a fan event, United ambassador Irwin said: "No, no, Harry is a Leicester player isn't he.
"Listen, we finished really, really poorly last year. When Ole took over, we were really struggling.
"We were 11 points behind fourth place, and we got ourselves up there, got ourselves to the quarter-final of the Champions League, and we fell away badly in the last two months, six weeks of the season. This is Ole's first pre-season, so he has got a chance to stamp his identity on the football team and the way he wants Manchester United to play.
"We've brought in a couple of young lads, who have got plenty of pace - I think something that we lacked in the last two-three years - and I think we need another couple of signings.
"It would be great to get another few signings in and go from there because it's a fresh start, a clean slate."