La Liga's president says Gerard Pique should choose his words more carefully after the Barcelona and Spain defender lashed out at perceived preferential treatment of Real Madrid players.
Javier Tebas said Pique's comments after a 2-0 win against France on Tuesday in Paris would only create "tension" between Spain's two biggest clubs.
"I believe he made a mistake, although how serious that is I can't say," Tebas said.
It came after the Barcelona central defender said that "I would never work for Real Madrid, I just don't like their values, even though I am friends with some of their players".
Pique evoked tax fraud cases against Barcelona teammates Neymar and Lionel Messi and claimed that Real's players had "pulled strings" to avoid punishment in similar circumstances.
Cristiano Ronaldo was accused by Football Leaks of hiding around 150 million euros in tax havens, accusations the Real Madrid star categorically denies.