The ruling has sparked a wave of protests in Italy including a flash mob on Monday outside a court in Ancona, the Adriatic coastal city where the rape is alleged to have happened.
Protesters shouted "Shame!" and held up signs saying "indignation."
Two Peruvian men convicted in the 2015 assault successfully argued the woman was too "masculine" to be a victim, the Justice Ministry said.
While the ruling by an all-female panel was made in 2017 it has only just come to light after Italy's Supreme Court of Cassation scrapped the judgement and ordered a retrial.
Italian women's right group, Rebel Network, which organised the protests, tweeted: "Rape does not fulfil a desire for pleasure, but an abominable hatred and contempt for the victim.
"It does not depend on how feminine you are, but on the hatred inside the rapist."