The Blues have been relatively quiet in the market so far this summer with Radamel Falcao joining on loan to replace free agent Didier Drogba and Asmir Begovic signed following the departure of Petr Cech.
The reigning Premier League champions had a £20m bid rejected for Everton centre-half John Stones last week.
Mourinho confirmed to Sky Sports News HQ he is in the market for a defender but otherwise appears content to enter the current campaign without making a splash in the market.
“In this moment we don’t want players,” Mourinho said. “Of course we must be ready because the market is open and if someone comes for one of our players with a bid, we must be ready to act.”
Mourinho did confirm the club was likely to seek a replacement for left back Filipe Luis after the club agreed to a deal to send him back to Atletico Madrid.
“We need a left-back because I think we will sell Filipe Luis, so we need to go to the market. But other positions we have no space.”