The Swede is said to have already agreed terms with the Rossonero, having confirmed negotiations in the past week.
But Leonardo says: "We'll leave (Rino) Gattuso alone with the transfer window, he has to think about the team and the matches, it's not the moment to talk about the transfer window, even if it's not something that bothers me.
"If something is imagined today, it is not said that it will be done in January. As long as the contract is not registered, it is not official. The market is not our priority, the important thing is to finish the end of the year at our best.
"If there is a dialogue with (Ibrahimovic's agent Mino) Raiola? We have dialogue with many people, we want to enhance the position of Milan, so it is normal to have daily contact with many people in the world of football."