The alleged admission came shortly after the she was taken into custody – four days after the alleged assault on a train in the suburbs of Paris.
The 23-year-old woman said six men cut her clothes and drew swastikas on her body, accusing her of being Jewish.
The woman has been detained for falsely reporting a crime, state prosecutor Xavier Salvat told AFP news agency.
She could face up to six months in prison and a 7,500-euro ($9,200) fine if convicted.
The case has sparked widespread condemnation amid concern that racist and anti-Semitic attacks are on the rise in France.0