Ralf Rangnick refused to entertain a fan's pleas after he was urged to make Erling Haaland one of three Manchester United signings this summer.
The incident occurred as the interim manager signed autographs outside Old Trafford following Saturday's goalless draw with Watford in the Premier League.
United are among the many European giants linked with Borussia Dortmund sensation Haaland, who has scored 19 goals in just 17 games this season.