"You had one job. You literally had one job and you couldn't protect us," she said of USA Gymnastics.
Biles spoke to reporters after a training session in Kansas City, Missouri, ahead of the United States Gymnastics Championships.
"The more I learn, the more I hurt. USAG failed us. USOC failed us. Many failed us. And they continued to fail us," Biles tweeted.
Biles told reporters that she struggles to take care of herself and see the doctors and therapists associated with the organization because of the deep distrust sowed by the Nassar scandal.
''It's hard coming here for an organization, having had them fail us so many times," Biles said. "We had one goal. We have done everything that they asked us for, even when we didn't want to, and they couldn't do one damn job."
The organization responded to Biles' comments saying they supported her and have learned from past mistakes.
"One of our goals is for our athletes to feel comfortable in speaking up and sharing their opinions, and we are listening to what they have to say. We will continue to work hard to demonstrate to Simone and all of our athletes, members, community and fans that we are working to foster a safe, positive and encouraging environment where athlete voices are heard."
CNN's Homero De la Fuente contributed to this report.