The Romanians became the first visitors to win in the Champions League at Old Trafford in three years thanks to Luis Alberto's swerving drive into the top corner from 25 yards.
The victory was not enough to see Cluj into the last 16 with Galatasaray progressing to the knockout phase courtesy of a better head-to-head record following their 2-1 win over Braga.
Despite the defeat, Ferguson was able to draw a number of positives from the performance of his young side, who created enough chances to get something from the match.
"It was a wonder goal that beat us," said the United manager. "We had a lot of good chances but with a goal like that we have no complaints, You can't do a lot about it.
"We had a young side out that did very well at times. I'm satisfied they put a decent performance in.
"It was a good experience for the youngsters. Nick Powell I though in the first half did quite well for us and Phil Jones had an excellent game. It's only his second game in about nine months so I'm very pleased with that part.
"We qualified earlier so it gave us a chance to experiment and play the players that needed a game. We gave some young players a bit of experience and that will hold them in good stead.
"We're into the next stage being winners of the group and there are some big names in there. We could face Shakhtar Donetsk, Milan, Porto."
"We qualified comfortably and the real tournament starts in February. The knockout stages are fantastic."