The 22-year-old scored against Stoke City in October but has failed to find the net since despite making 27 appearances in all competitions during 2012-13.
However, Rooney dismissed concerns with Welbeck's profligacy, instead highlighting the youngster's work rate and other positive contributions to the Premier League leaders.
"We're not too concerned about him not scoring too many this season," the former Everton man told United's official website.
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"He hasn't been playing up front a lot - he's been playing out wide. He's been doing a job for the team, which, as players, we're all grateful for."
Rooney - who came in second behind Steven Gerrard at the FA's England Player of the Year awards on Sunday night - is in fine form for United, with 10 goals in his last 10 games, but recalls receiving similar criticism to that which Welbeck is currently receiving when he was not playing as an out-and-out striker.
He continued: "Everyone labels Danny as a striker and I have had that at times when I have played in different positions. Someone will bring up the fact that I haven't scored for eight games when I hadn't played up front!
"Danny has been out wide a lot this season. He is a great player and his time will come when he gets that run up front. I am sure then he will score goals."