Klopp took part in the tribute match between former Dortmund pair Lukasz Piszczek and Jakub Blaszczykowski.
Ex-BVB coach Klopp took charge of Blaszczykowski's side for the testimonial.
He later smiled: "It's a lifelong dream come true. I wanted to have that again.
"Just a few months ago, I was given an emotional farewell in Liverpool. Today it was very emotional again.
"Some people might say that today he's like this and tomorrow he'll be like that. I explain it like this: when you have three children, you love them all. And that's the same with my three clubs. I love them all."
On what he has been doing since leaving Anfield, Klopp added: "I'm working, but not as much as I used to.
"I'm not just doing nothing, but sometimes I am. I don't miss anything!"