According to the report, the Italian manager will allow the striker, who has been training alone since Monday, to return with his team-mates only in the event he notices genuine signs of a change in Costa's stance.
Conte was initially expected to hold a one-on-one with Costa on Tuesday to clear the air.
The striker, who received an offer from the Chinese Super League club Tianjin Quanjian complained of a back injury last week, sparking a row with Chelsea's manager and the medical staff.
Conte then decided to drop him from the squad for the game at Leicester City on Saturday.