The boss felt the Reds adjusted well to the blow of having Nemanja Vidic's red card early in the second half.
"After the sending off, we had to be very patient and play with even more discipline to avoid conceding a goal," said Sir Alex.
"We still went looking for the victory though, and thankfully we got that decisive goal.
"Even if we missed a lot of chances in the first half, I'm very pleased with our performance - it was a great team performance.
"Winning this title will hopefully give us some extra impetus for the rest of the season."
The manager reserved special recognition for United's match-winner in his post-match press conference.
"Wayne Rooney was named man of the match and he certainly earned it. He played really well, scored a great goal and proved what extraordinary qualities he has."
Like Rooney, Sir Alex paid tribute to the part played by supporters in getting United to the final and ultimately to the podium.
"The support from the fans was fantastic and we'd really like to thank everyone for that. It was a great tournament, and one I'll look back on fondly in the future."