Lookman spent the second half of last season out on loan at RB Leipzig, and had been linked with a return to Germany, but Silva has no said he will stay.
"I don't like to talk about every day him," said Silva.
"I have already told you my thoughts about him and his skills as a player. Our decision is already made.
"Of course. He stays in our plans. He has to work to take his position in our squad.
"He is fit and training with the team tomorrow and this morning."