The champions won their opening games against the Czech Republic and Turkey but were beaten 2-1 defeat by Croatia and now must take on Italy in Paris on Monday in a repeat of the 2012 final.
"I accept it (the criticism) because it goes with my position," Del Bosque told AS newspaper. "Had I made changes and we lost, people would have said 'why change something that works?' But there was nothing to alter."
Winger Pedro had voiced his frustration before the Croatia game after playing just nine minutes.
"If you don't play, it isn't worth it coming just to make up the numbers," he said.
The Chelsea winger later apologised. Six Spanish players have come off the bench so far and only two of those substitutes, Bruno and Aritz Aduriz, have played more than 50 minutes each in the tournament.
"It hurts me not to be able to use more of the other players," Del Bosque said. "But I only have words of gratitude to those who have not played. They have shown availability, they have helped each day in training and in the camp."