The Chilean guided City to a double this season - adding the top-flight crown to their League Cup win after a tight title race with Liverpool.
That capped off an impressive debut campaign in England for Pellegrini, who saw several of his signings from last close-season - such as Alvaro Negredo, Fernandinho and Jesus Navas - play major roles.
The former Malaga boss is keen to recruit further players ahead of his second season in charge, insisting City are not yet the finished article.
Asked by the club's official website whether there were likely to be changes to his squad, Pellegrini said: "Maybe. Maybe we are going to see what is the best way to improve.
"I think one of the most important things for me is to have an ambitious mind.
"It's very important to win titles. We have already won titles but we must analyse all the good things we did, the bad things and where we must improve.
"(Also) which is the best way to do it so we have a lot of work (to do)."
City were eliminated by Wigan Athletic in the sixth round of the FA Cup while they were beaten in the UEFA Champions League last 16 over two legs by Barcelona.
Champions League success remains a target for City, and Pellegrini was pleased to lead the club past the group stages for the first time.
"Everyone is talking about Europe - I think we were very unlucky this year in the Champions League because the sending off (of Martin Demichelis in the first leg) against Barcelona changed that match," he continued.
"I think tactical games in the round of 16, you must also have tactical work and we were also doing very well.
"We were eliminated but I think we made a big step this year in qualifying for the round of 16 - we beat Bayern Munich in their own stadium, we were on the same points as Bayern.
"It was an important step and I hope next year we can continue a stage (further)."
