Inler was brought to Leicester over the summer and was expected to have a big part to play for the Midlands side this season.
However, the Swiss midfielder has made just three Premier League appearances to date, and when on the pitch he has looked off the pace.
"Of course, it's not easy to change the mentality from Italian football," Ranieri said. "It's more tactical and slower than English football. He's getting better but must continue to improve."
Inler was Leicester’s marquee summer signing, but his failure to hit the ground running has not been as big a blow as many were expecting.
The Foxes have been in wonderful form without the 31-year-old, and they currently sit in third place in the top-flight table.
The partnership N’Golo Kante and Danny Drinkwater have formed in the middle of the park has been excellent, and Inler now faces a fight to win his place back.
If Inler can find his top form he will add further strength to Ranieri’s side, as they look to extend their brilliant run of results for as long as possible.