"The Egyptian government has a responsibility to take legal measures to prevent sexual violence and to prosecute people who are involved in sexual violence," Earnest said.
Earnest also condemned the suggestion by some Egyptians that the women had put themselves at risk by joining protests with men.
"The idea that some Egyptians are blaming the victims for being raped and assaulted is abhorrent," Earnest said. "We strongly condemn these views and reaffirm the right of women to express themselves in public squares alongside men as well as the responsibility of the Egyptian government to protect them."
Muslim Brotherhood-led protests against the Egyptian government have intensified in size and violence in recent months, as have reports of sexual assault.