Valdes chose to pull his youth team out of the third-place play-off against Everton at the Youth Otten Cup.
"I've taken the decision personally," the former goalkeeper said.
"My decision is based solely on safeguarding the health of my young players, we're not happy with the organisation in terms of rest time between matches.
"Having lost the semi-final today, there hasn't been a gap for recovery, not even an hour between matches.
"It's an abnormal fatigue for their age and for the stage of pre-season that we're in.
"I want to say that, with the high risk of injury in my squad or something more serious on a cardiac level that could occur in not taking this decision, I assume all responsibility for what this may have caused.
"I will always protect my players without thinking about the consequences."