Spanish clubs in European competitions are the most playacting, shithousing, non-footballing teams in the world, and the refs encourage and reward it. Bar Barcelona in their prime, not a single Spanish side I've seen actually play good football. They are football's antithesis. Real Madrid, Real Sociedad, Villareal, Sevilla, Atletico - not a single one of them actually display their alleged 'passing prowess', and spend more time rolling on the floor and exaggerating contact than actually trying to play the game.
Unless the referees in these games are thoroughly vetted and stay competent in the games themselves, I have no idea what can be done about it.