Atleti supporters burned Aguero shirts after his move to City was confirmed last week.
El Kun said on his website: "I had the chance to not sign a renewal and be a free agent in 2012. However, I personally decided to renew. Now with my transfer the club get a big sum of money that will help to improve the team, that otherwise they would not have received.
"I wanted to renew as a way to give back to the club and its fans everything they have given me."
Aguero was unequivocal when asked if he made any mistakes during the transfer saga.
''No. I also understand that time heals everything and put things in place. I have to say thanks to the club [Atletico Madrid], its employees, my teammates and the fans. I have given so much and I answered them with dedication and professionalism. Five seasons were very good.
"With 101 goals and 2 titles, I will never forget Atletico. It's clear that I'd have to say goodbye properly. This is the moment to do so. And I wish my former colleagues, including many friends, all the best for this season."