Giggs struck in the final moments at Carrow Road.
"To score the winning goal with the last kick of the ball in his 900th game... I think his career deserved that," the manager told MUTV. "It was a marvellous finish and a great cross from Ashley Young.
"For a player to play for one club for 900 games is exceptional and it won't be done again - an amazing career and an amazing man."