A Westchester teen claims she was cruelly harassed by classmates after reporting that she was sexually assaulted at a party — and Croton-Harmon High School in Croton-on-Hudson did nothing to protect her.

When the alleged victim asked for a safety transfer to a different school, administrators denied her requests, she charges in a Manhattan Federal Court lawsuit.

The girl, identified in court papers as Jane Doe, told police she was sexually assaulted in October 2016 by two male classmates while a third stood lookout at an off-campus party.

Even though the freshman quickly reported the assault, the accused attackers “were popular students at the High School and had already begun a campaign of bullying and harassment” toward her, she charged in court papers filed against the district.

One attacker threatened to beat the girl “and break her legs” if she came to school, while others inundated her in social media messages — including a Snapchat image of a young girl “passed out, face down, lying on the ground in a revealing dress from the night of the off-campus party,” according to the lawsuit.

Administrators allegedly ignored pleas from Jane Doe and her family to keep the boys away from her, despite orders of protection she’d obtained against them. The family eventually rented a home in a different school district to allow their daughter to attend classes, she claims.

The school district declined comment on the litigation.