He has thus far appeared just five times for Pellegrini's side following several injuries and a bout of illness.
And while his manager continues to back him, the South American admits he may soon run out of patience.
"It is very difficult to know with Jovetic," said Pellegrini, quoted in the Sunday Mirror. "But I believe what the player says and if he says he has a muscle problem I'm absolutely sure he has a muscle problem.
"We hope it was bad luck for the first part of the season and we can use him in the second half of the season because he is a very important player.
City are without top scorer Sergio Aguero, and would welcome a fully-fit Jovetic.
However, the forward had a reputation in Italy as a player with an unusually low pain threshold.
But Pellegrini remains upbeat about his front-man.
"It's impossible for the players to be 100 per cent for every game, but there are different degrees of injuries. I am optimistic," he said.
"At the end of the season, maybe I change my opinion. But at the moment, I continue trusting him."
Next up for City is a clash against West Ham in the first leg of the League Cup semi-final.
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