"It was a very intense game with the two best teams in the country," he said.
"We were unlucky to lose it. We know Aguero is a fantastic finisher but we gave him a lot of room.
"I was pleased with the performance and thought we did really well.
"There were lots of plus signs, our form is good, I have no complaints. If you look at the whole thing, it`s not a bad day for us in terms of the performance level.
"You don't want to a lose a derby game, but we're okay."
Ferguson claimed that Manchester United were merely reverting to type by losing Monday's derby clash with Manchester City at Old Trafford.
Whilst victory would have taken them to the brink of a record 20th league title, a 2-1 loss means they will have to wait at least a couple of weeks for confirmation of their status as Premier League champions.
It was not what Ferguson wanted.
But after watching Sergio Aguero condemn United to their first defeat since November and cut their lead at the top of table to 12 points, the Scot was not that surprised.
"If you look at the history of our club, we always make it difficult for ourselves," said Ferguson.
"We have our supporters hanging on the edge of their seats every year.
"We have a 12-point lead but we won't be taking anything for granted.
"The plus point from today [Monday] is that we only have seven games left now. As each game goes along you whittle them down.
"We have Stoke on Sunday. The support will be great and we will have a go. We have to kick on now."
There does seem to have been an extended hangover from United's Champions League exit to Real Madrid last month, which was followed last week by an FA Cup defeat at Chelsea.
Ferguson will want his side to stabilise themselves before needless anxiety starts to take hold.
And, after 10 games without a goal, he could do with Robin van Persie getting one, even if it was the Dutchman's brutal free-kick that created the panic that ended with Vincent Kompany's equalising own goal.
"Robin was absolutely fantastic," said Ferguson.
"We were a bit lucky with the goal because it was an own goal off Kompany. But it was a fantastic free-kick."
The United boss did feel Carlos Tevez was interfering with play from an offside position when man-of-the-match James Milner drove City in front.
However, Ferguson felt he had a contender for the game's best player in Phil Jones, who was outstanding in central defence.
"Phil was magnificent," he said.
"He has only played two games at centre-back this season. That tells you what a good player he is.
"The boy could be anything. At 21 he is a man."
Ferguson also confirmed Ashley Young was a doubt for Sunday's trip to Stoke after coming off worst in a challenge with Gareth Barry.
However, he is more concerned about bolstering his defensive strength, with both Nemanja Vidic and Jonny Evans missing on Monday.
"We want to get a centre-back fit," he said.
"That would be important for us."