Porto not planning to sell Chelsea target Pereira
Chelsea had a bid for the Uruguay international turned down in the summer and they were expected to come back with an improved offer next month when the transfer window re-opens.
Da Costa said: "I have offered a guarantee to the coach that no important players will leave the team in January, and that includes Alvaro Pereira.
"I think the chance to do a deal for this player has passed, and that is good news for us.
"Now is the time that rumours start spreading in the papers, but I am used to that."