The Hollywood star and his journalist father Nick were placed in handcuffs and driven away by secret service agents after they ignored three requests from cops to leave the area of a humanitarian protest.
Clooney, who had given a speech on the steps of the Sudanese embassy, his father and 13 fellow protesters were arrested after they refused to clear the area and were charged with disorderly crossing a police line.
As he was led away, Clooney admitted his arrest was "a deeply humiliating thing".
He was released after two hours in custody and held an impromptu press conference with his dad urging U.S. politicians to act now to put a stop to Sudan's President Omar al-Bashir's ruthless quest for oil and the atrocities he's accused of committing against his own people.
Clooney warned that the people of the newly-independent South Sudan faced starvation as they hide out in caves to avoid al-Bashir's attacks and bombing raid on their homes.
He told reporters, "What we've been trying to achieve today is bring attention to an emergency, one that has about a six-week timetable for war... The rainy season starts soon and a lot of people are going to die from it. Our job right now is to try to bring attention to it.
"One of those ways was apparently getting arrested. I guess people aren't allowed to hang out at the Sudanese embassy. I didn't know that!
"There are people dying every day... What is the real looming danger is this: they are trying to choke these people out and get them to leave... They are not leaving their land, they are hiding in caves... The best estimates are tens of thousands of people are going to die from starvation that is man-made. This isn't a famine, this is a man-made tragedy by the government of Khartoum to get these people out, so it's immediate.
"We hope that this (his arrest) brings attention to it; we hope it helps... We hope it gives some more political will... and we hope that people really understand there is a ticking clock on this and we really need to get moving."
The Descendants star has been campaigning for international humanitarian help in Sudan for years, and he travelled to the African nation last week (05Mar12) to gather first-hand information about the crisis ahead of a meeting with members of Congress at the Senate Foreign Relations Committee on Wednesday (14Mar12).