The court decision on Wednesday sparked widespread outrage in France, with one feminist group saying it sent a "catastrophic message" that rape is permissible.
Ten men were acquitted in the case while four defendants were handed down sentences ranging from one year in prison to three years suspended for raping one victim, identified only as Nina, now aged 29.
Prosecutors had called for eight of the accused to be given sentences of between five and seven years. They made no sentencing recommendations for the other six accused.
"The verdict is too far from the prosecution requests, both on the sentences given and certain acquittals. It does not take into account how the crimes were committed," said Nathalie Becache, chief prosecutor for the Paris suburb of Creteil.
She said the verdict also did not take into account the "particularly serious physical and mental damage" done to the two victims.
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The two victims said they had seen a "judicial disaster" after the verdict in the attacks, committed in the poverty-stricken housing schemes of Fontenay-sous-Bois between 1999 and 2001.
They said they were repeatedly raped in sordid places -- in basement cellars, stairwells and car parks. One of the victims said she was a virgin when she was first attacked one night when she was returning from the cinema.