Petrov joined Bolton on a free transfer on Thursday after having been released by City.
“It was frustrating, but not because I didn’t play – I understand, because they are buying big stars now for so much money,” Petrov said.
“Every time I played on the pitch I showed that I have a place in this team, but okay, the decision is the manager’s.
“But the worst thing is that the communication in this club with the players who do not play is not professional.
“I am 31 years old and I felt like I was 13 there. Nobody spoke with me about my situation – they knew that my contract was finishing.”