According to the Proto Thema newspaper, violence erupted on Thursday afternoon, as migrants desperately seeking to leave for continental Europe assaulted police officers and broke into the camp registration office.
Order was restored in the camp after the coast guard intervened, the newspaper said, adding that one police officer was injured.
Some 650 undocumented migrants and refugees are provisionally detained at the Leros camp.
Hundreds of migrants coming ashore on the Greek islands find themselves locked up for months at so-called hotspots.