The singer just explained her reasoning for taking down the video of her having a solo dance party in her hotel room in Los Cabos, Mexico ... Britney says she made the change "because so many people said so many mean things."

Britney keeps the replies off on her IG, which is where the video in question was originally posted, but it sounds like she still pays attention to what folks say about her elsewhere on the internet.

BS admits "it saddens me people say mean things about me" but adds ... "I'm so damn sick of people saying they are concerned and if you don't like the way I move, f*** off and don't watch it !!!"

As we reported ... Britney shared the video earlier this week during a getaway to Cabo.

She's since returned to the States, clutching a stuffed rabbit during her journey back.

Britney says she didn't think she was going to go on the trip in the first place because she was feeling sad, but then her mood changed when she got to her hotel and she started playing music and felt like dancing.

She says, "It is a f****** miracle from God that I played and danced, period."

Britney says she has more dancing videos on her phone, but it sounds like those won't see the light of day.