Lopez is the undisputed first choice at the Bernabeu ahead of Iker Casillas, but the Spaniard has been criticised for his part in defeats to Barcelona and Sevilla in recent weeks.
"Since the start of the league, Diego Lopez has been under great pressure," Buyo told AS. "Not just to wear the shirt of Real Madrid but the media obviously, and sometimes rightly, reviews him.
"But I'd say he's made no major mistakes. He hasn't committed any great faults or errors that have been decisive in a defeat."
"Some of the criticism has been unfair, although no one can question the merits of Iker and everything he has done."
Casillas will start tonight's Champions League quarter-final first leg against Borussia Dortmund.