The Red Devils are yet to win a competitive game under the Dutchman, who replaced David Moyes at the helm following last season's fall from champions to seventh.
While speaking at Soccerex in Manchester, Charlton expressed no fear over United's position after the club spent around £150m on six new recruits in the summer.
"We've got nothing to worry about," the Manchester Evening News quotes Charlton as saying. "He's got the world at his feet, the new manager.
"What we need to do now is put the players in the right places and the ball in the right place, but that's harder than it sounds."
United will take on Queens Park Rangers in the Premier League at Old Trafford on Sunday.