Porto have insisted that they will not sell Joao Moutinho for anything less than his £30m release clause following interest from the Premier League.
Manchester United and Tottenham Hotspur have been strongly linked with the Portuguese playmaker, but his club are intent on keeping him.
"Clubs cannot just not sell. We really want him to stay but this is football and there are such things as release clauses," Porto manager Vitor Pereira told Abola.
"The only thing we can do is achieve results with what we have got."
United previously lodged a £20m bid for the player, which was ultimately rejected, while Spurs could be willing to match his buyout clause.
Moutinho, who has been capped 48 times by his country, has three years remaining on his current contract.
