The 27-year old man, who arrived in Greece in March 2018, was detained after an argument on Wednesday between two groups at the camp, a police official said.
He was arrested on Thursday, accused of being a member of a terrorist group and participating in homicides. He is expected to appear before a prosecutor later in the day, according to a police statement.
Police said such arrests were rare.
Greece, on the front line of migration into Europe, promised on Wednesday to build new reception centres for asylum seekers and cut the maximum stay in camps on its now-overcrowded islands.The country bore the brunt of a large influx of refugees and migrants into Europe in 2015 and 2016, many arriving via its outlying Aegean islands close to Turkey.