The 28-year-old Brazilian midfielder, capped five times for his country, signed for City from Shakhtar Donetsk on a four-year deal last month.
"My performances will dictate whether I can make World Cup squad, but my first aim is to play well for Manchester City rather than think about the World Cup," BBC Sport quotes Fernandinho as saying.
"It was very important that I was seen as a top target. I'd like to repay the club by helping them win as many games and trophies as possible."
Manchester City begin their pursuit of the Premier League title on August 17 with a game against Newcastle United at the Etihad.