The Portuguese manager has said that he would prefer to lose the players on free transfers if new contracts are not agreed than sell them in January.
"The most important thing is for the club to try to defend its interests," he said. "We know these players are of high importance."
New deals have been offered to Kalou and Drogba while a decision is yet to be taken on Frenchman Anelka.
"That's why the offers are on the table, apart from with Anelka, end of story," added Villas-Boas.
"We will try to get them to reach an agreement."
Chelsea are currently third in the Premier League, three points behind the pace set by the two Manchester clubs. The Blues will host Everton in the Saturday's evening kick-off.