"We were too long in delaying our crosses. We should have got the ball in earlier," Ferguson said on MUTV. "But we just didn't get into the space behind them, it just didn't happen for us."
He added: "Norwich got plenty of men behind the ball and closed out all of the spaces and we just couldn't get our crosses in."
Despite the obvious disappointment of not being able to extend their five-match winning streak, Ferguson felt Norwich also deserved credit.
"There are times you have to recognise when your opponents have played beyond themselves," he said. "It was a game in which you have got to give Norwich lots of credit for working so hard. It was a really special effort."
Anders Lindegaard had deputised for David de Gea in goal, after the Spaniard who was troubled by a wisdom tooth extraction, while Rooney was missing because of tonsillitis.
The forward sat out England's midweek friendly in Sweden because of an ankle problem.
United's medical team will now assess Rooney in the run-up to the Champions League Group H trip to Galatasaray.
Ferguson said: "We hope he will be in on Sunday - we will see what he is like then. If he does [come in] hopefully we can get him ready for Tuesday."