"I am hoping with the world-class players we have here that we will go and lift a trophy, which is what I want to do in my career," Walker told the BBC.
"I was unfortunate at Tottenham. We made it so close in the last two seasons, it was just that sometimes we were unlucky. Sometimes we just didn't have that little bit of edge.
"I needed a new challenge. This would have been my ninth season at Tottenham. Sometimes you need to come out of your comfort zone a little bit."
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Walker, who was signed by City for 50 million pounds ($64.92 million), according to British media reports, said he was excited to work with former Barcelona and Bayern Munich boss Pep Guardiola.
"The manager was a big thing for me (coming to City). I wanted to come and play under him," the 27-year-old added.
"He's worked with Dani Alves and all the top players at Barcelona, plus (Philipp) Lahm at Bayern Munich, that was a big attraction for me."
Walker is set to face his former team mates on July 29 when City meet Spurs in a pre-season friendly in Nashville.
City, who finished third in the Premier League last season, visit newcomers Brighton and Hove Albion in the opening game of the new campaign on Aug. 12.
($1 = 0.7702 pounds)
(Reporting by Hardik Vyas in Bengaluru)
