The Canaries created a number of chances at Old Trafford, including a strike from Anthony Pilkington which hit the post.
However, United boss Ferguson has claimed that his side were good value for their 2-0 win.
"We were far too slow in the first half," Ferguson told Sky Sports News. "But in the second half we did better.
"We deserved to win because we were the only side that wanted to.
"Credit to Norwich because every time they counter-attacked they got something out of it."
United remain top of the Premier League table on goal difference over local rivals Manchester City.