The Dutchman said his side had been "playing against 12 men", accusing opposition coach Christian Streich of influencing the referee's decisions with his "shameful, brutal and disrespectful" behaviour.
"I've never experienced anything like it," Verbeek told Sky. "He acted like he was possessed every time something happened, and the way he insulted me is not on.
"It's incredible what he has done.
"Of course Freiburg try to eek an advantage out of the atmosphere, but if the referee cannot remain impartial, then he should be doing something else.
"The German FA (DFB) have got to do something about it, but they don't. They just keep defending themselves.
"This is the first time I say something about referees, but this was shameful. He's (Streich) no colleague of mine and I won't accept an apology."
The DFB have invited Verbeek to explain his comments before discussing what, if any, action to take.