The Frenchman dismissed suggestions a more lucrative contract was the reason behind his £24 million move from Arsenal to City.
Nasri was also linked with United as he entered the final year of his contract, but said: "I can let people think what they want. Me, I know my choice and my choice is about football.
"We will see at the end of the season when we will lift a trophy, we will talk about my choice again and we will show that everyone who was thinking about money that they were wrong.
"I think City can win the title. It is the biggest challenge to Manchester United.
"When you see the investment of the last three seasons you see they bring some muscle and real quality players. World-class players are not scared to come to Man City and you can see that with Sergio Aguero. I am confident.
"I trained with big players and was happy to train with them and saw real quality. I know I made the right choice in coming here.
"I'm confident we can win a trophy because I saw the quality on the pitch. I said it was a club of the future and I am still convinced of that."
While looking forward to a new challenge at the Etihad Stadium, he was also eager to set the record straight when talking about his former club.
Arsenal followers were infuriated at critical comments from Nasri that they were not "passionate".
But he said: "You've got that wrong. I never said Arsenal fans were not good. I just said I saw real passion when I signed here and when I signed for Arsenal it was a little bit different. Cesc (Fabregas) said as well, the difference between Highbury and Emirates is the atmosphere, but don't get me wrong, I never said Arsenal fans have a lack of passion."
Nasri will make an immediate return to North London as City visit Tottenham Hotspur on Sunday and manager Roberto Mancini looks to find a way of accommodating him into a side that has an abundance of attacking riches.
The Italian welcomed the problem as he was an admirer of the midfielder when he coached Inter Milan.
"I'm happy because he's here. He's a fantastic player, a young player and he's very important for the squad and the club," said Mancini.
"He knows the Premier League very well and I wanted him when I was at Inter and it was a little difficult.
"I think now he's better, he was very young five years ago and I think he can improve."
Source: AFP
Source: AFP