The 19-year-old Serbian joined City from Fiorentina in the summer transfer window and has made eight appearances for the league champions.
Nastasic says team-mates Aleksandar Kolarov, a fellow Serbia international, and Edin Dzeko have helped him adapt to life in Manchester.
He told SportSport: "I have managed to adapt to life in England but of course I still need some time to feel really at home.
"At first it was quite hard but my team-mates really helped me, especially Aleksandar Kolarov and Edin Dzeko."
Nastasic admits it is difficult to compare the Premier League with Serie A but feels the English top-flight is a stronger division.
"If you ask me, then it is hard to compare Italy and England," he said.
"Football in the Premier League is much stronger, much tougher, and this game is also more popular in England than in Italy.
"Clubs are stronger, and players also have much more chance to succeed in world football."