Athletic Bilbao president Josu Urrutia has warned that Javi Martinez will only be allowed to leave for the €40 million (£32m) fee stipulated in his release clause.
The 23-year-old midfielder has been strongly linked with a move to one of Europe's traditional big guns, with Barcelona and Bayern Munich both credited with an interest in the Spain international.
Urrutia has declared that Athletic are not interested in parting company with Martinez and ruled out the possibility of the player being sold on the cheap.
"If someone wants to take Javi Martinez, they will have to pay what the release clause in his contract says," Urrutia said in a press conference.
"For a player to leave Athletic, he must first come to us and say that he wants to go. Then, a club must match his release clause.
"If a club is willing to pay, but the player wants to stay, then he will stay. We are not a selling club."
The player's agent recently dismissed rumours that a deal had been struck with Bayern.