The Tigers were 4-1 down with twenty minutes to go at Old Trafford but a spirited second half performance by Phil Brown's side saw them reduce the deficit to 4-3 at the final whistle.
"We're a bit low after that performance," Fergie told MUTV.
"We didn't take our chances and that's annoying.
"We should have scored 10 or 11 but we frittered our chances away and we've almost been left embarrassed.
"The only positive from today is that we're creating chances. We're playing some fantastic football at times.
"Ronaldo could have scored four or five and I don't know how many chances Berbatov made today but we could have scored a lot of goals.
"We missed all our chances, they've come back to 4-3 and we're left scrambling to get a victory."