House Intelligence Committee Chairman Adam Schiff said President Donald Trump is "willfully fanning the flames" of racial unrest and violence because his campaign believes it helps his re-election chances.
A White House summit planned for Saturday between Kosovo's President Hashim Thaci and Serbia's President Aleksandar Vucic was postponed on Thursday, one day after Thaci's indictment on war came charges became public.
Richard Grenell previously served as President Donald Trump's ambassador to Germany.
"Any U.S. diplomat who acts like a high commissioner of an occupying power must learn that our tolerance also knows its limits," Wolfgang Kubicki, a deputy speaker of parliament said.
The administration is "pleased with this decision because Iran diverts its economic resources away from its people to spread violence and instability across the globe," the U.S. ambassador to Germany said.
"If people like U.S. Ambassador Richard Grenell believe they can dictate like a lord of the manor who rules in Europe and who doesn't, they can no longer remain in Germany as a diplomat."
Richard Grenell broke with diplomatic norms to say he wants to "empower" conservatives across Europe.
Richard Grenell has been accused of making threats towards German businesses over imminent U.S. sanctions on Iran.