The Scot said that he was "pleased" with his team's first-leg performance and singled out goalkeeper David de Gea for praise after the game.
"I think it was an interesting match. There were chances at both ends. David de Gea made three or four terrific saves and we missed some really good chances ourselves," he told Sky Sports News.
"We sat back off them too much in the first half and they had a lot of play around the edge of our box which is not healthy or good to watch. It was unlike us in many ways but we changed it around in the second half and put Danny Welbeck around Xabi Alonso. It made a great difference and the ebb of the game definitely changed."
Ferguson went on to say that he was satisfied with his side's second-half display and the number of chances they created, but expressed concerns over their ability to keep possession.
"We had a really good start to the second half and, all in all, created a lot of chances with good attacking football at times but we've not had the possession we should have. Real won the possession without question but they were at home and it's a difficult place to come," he added.
Danny Welbeck headed United in front on the night but Cristiano Ronaldo later struck against his former club to ensure the game finished in a draw.