"I have a message for President Trump, from one Republican to another. This is a disaster," Jenner said in a video she tweeted, while looking directly at the camera. "And you can still fix it. You made a promise to protect the LGBTQ community. Call me."
Jenner came out as transgender in 2015. On Wednesday, the Trump administration withdrew protections set forth by the Obama administration for transgender students in public schools, which let them use bathrooms and facilities corresponding with their gender identity.
"I have a message for the trans kids of America. You're winning," Jenner also said in the video, encouraging them to make their voices heard. "I know it doesn't feel like it today or every day, but you're winning. Very soon we will win full freedom nationwide and it's going to be with bipartisan support. You can help by checking out the National Center for Transgender Equality and letting Washington hear you loud and clear."
Jenner later called out Attorney General Jeff Sessions.
"Now I have a message for the bullies: You're sick," the I Am Cait star said. "And because you're weak, you pick on kids, you pick on women or anyone else you think is vulnerable. Apparently even becoming the attorney general isn't enough to cure some people of their insecurities."
Interestingly enough, this past April, 67-year-old Jenner praised Trump for his statement that he would be fine with Jenner using whatever bathroom she chooses at Trump Tower, when Trump was asked about it during a Today interview with Matt Lauer. Jenner then went to Trump Tower in New York City and used the women's restroom to make a statement.
"OK, last week Donald Trump said I could take a pee anywhere in a Trump facility. I am going to go take a pee in the ladies' room," she said.
The Olympic champion also took a shot at then presidential candidate Ted Cruz for his statements on transgender issues, including Cruz previously stating that supporting equal treatment to transgender students is "lunacy."
"Thank you, Donald, I really appreciate it," Jenner continued. "And by the way, Ted, nobody got molested."
Watch the video below to hear Jenner explain why she was previously against gay marriage.