Anthony Pilkington's second-half header condemned United - missing the ill Wayne Rooney - to a first league defeat since September.
Ferguson said: "We're disappointed to lose the game but we have to give credit to Norwich for the way they fought and battled for every ball on the pitch.
"They defended fantastically well and the goalkeeper also had a really good night so it's disappointing.
"It was a marvellous cross and a marvellous touch for their goal so our goalkeeper could do nothing about that. They deserved the win just because they worked so hard for it.
"The players are used to making comebacks and we're always a threat in the last minutes of matches. We had a lot of half-chances but it just wasn't our night."
Rooney was out with tonsilitis, and Ferguson said: "We always miss our good players but we had plenty of good players on the pitch."