The 25 year old has not featured in Conte's starting line-up in the Premier League since the 2-1 home defeat to Liverpool in September.
"Oscar's future is Chelsea. For me he is an important player in my squad. He is in good form.
"It is logical that I have to choose the starting XI every week but Oscar is a great player and, for me, he stays in Chelsea.
"It's important send this message to all. He will stay with us because I consider him an important player."