Mancini told Sky Sports 1: "It was incredible - they deserved this. To win it like this is incredible. I don't think I've ever seen a finale like this.
"We didn't deserve to lose, we had a lot of chances and we deserved to win the game and championship.
"It's fantastic for the club and the supporters after 44 years. It's been a crazy season and a crazy last minute."
The Italian added: "Five minutes from the end, I didn't think we'd win this game. But we deserved to win this and deserved to win the title. We were on top for 20 games.
"I think for us it was really important to start winning this championship, Manchester City can have a big future now."