The 26-year-old came under close scrutiny in his second campaign with the Premier League side, after only managing to score twice in 28 games.
Nasri was widely criticised for shying away from Robin van Persie's last-gasp free-kick, which saw City lose 3-2 to rivals Manchester United in December, with the Old Trafford Outfit going on to cruise to the Premier League title.
But the France international has banished his demons and is determined to help City regain their league crown.
"I'm feeling more relaxed, but the last few months were very trying for me," he told FIFA.com.
"Emotionally, I went through several moments of doubt and reassessment. Some of the criticism I got hurt me, and lots of bad things were said.
"I made mistakes, I know, but I'm not the ugly duckling that some people seem to think.
"I've learnt from my mistakes and I feel more mature now. I'm still young and I know I have a lot to learn. These last few months have made me grow as a man.
"We didn't manage to win a single trophy (last season), and that's disappointing for a club with the standing of Manchester City. We had a very testing year but we'll learn from our mistakes to have an excellent season next year."
