Ahead of tonight's Euros quarterfinal against Germany, De la Fuente paid tribute to the former Real Madrid midfielder.
Kroos will retire after the Euros and De la Fuente said: "Football will never leave him, it will be he who leaves it and, incomprehensibly, wants to leave it now.
"He has been very good for Germany and it is a pity that he has decided to stop playing.
"To stop him we have thought about tying his feet, but I don't know if UEFA will let us do that!"
De la Fuente continued: "What I can say is that we see ourselves strong and with the potential to fight for everything, which is what we came here for. Tomorrow we are very excited about this meeting, although we know that anything can happen.
"I am still the same today as a month ago. I take care of what I control with my coaching staff. I am not concerned with what is said outside."