The actor was led away in handcuffs after being warned three times for crossing a police line while protesting on the steps of the Sudanese Embassy in Washington.
George was joined by his father and a number of activists who accuse Sudan's president, Omar al-Bashir, of provoking a humanitarian crisis.
He said earlier that he hopes to draw more attention to the issue. And added that that "we're going to have a real humanitarian disaster," if action is not taken in the next three to four months.
The 50-year-old is co-founder of the Satellite Sentinel Project which uses private satellites to collect evidence of crimes against civilian populations in Sudan.
Last week he visited the volatile border region between Sudan and South Sudan, where he narrowly escaped a rocket strike.
The star saw burned-out villages and met with residents made homeless after aerial attacks by Sudan's military.