The Canaries - reborn since the international break - produced another composed display to secure a third win in five Premier League games with a fine header from Anthony Pilkington, once on the youth books at United, on the hour.
"Norwich deserved their win because they worked so hard for it, although we had a lot of possession and one or two half chances. We didn't create enough great chances. It just wasn't our night," Ferguson said on ESPN.
"Their goal was a marvellous cross and a great touch for the header. There was nothing our keeper could do about that.
"So you have to give credit to Norwich because they battled well, and their goalkeeper had a good night as well, so it is disappointing."