Levante lost 2-0 at home, with Valenciaa's celebrations infuriated the home support, which included Los Che defender Eray Comert taking the corner flag and sticking his shirt at the end of the pole to wave it in front of the away support.
Castro said afterwards: "Respect is always very important. You have to know how to win and how to lose. People who don't know how to lose or don't know how to win, contribute nothing to football.
“The squad's morale isn't good. No one at Levante is in a good place right now. The job isn't finished, and there are games where we should have gotten more points, and others where nobody expected us to score.
"We have to go out and win the next game and improve in different areas. In football, the brain is more important than the physical aspect.
"The brain is what makes the decisions, and that's the most important thing. We have to keep working and believing that it's possible.”
Castro added, “I believe it. Tomorrow morning I'm going to Buñol, eager to train and give my all for the club. When I arrived, I knew the club was in a difficult situation. I came because I believe it's possible.
"If there comes a day when it's mathematically impossible, I'll say so. In the meantime, I'll keep working.”