Melania Trump just got what she was after ... the man who posted the YouTube video suggesting Barron had autism is taking the video down.

The guy who posted the video says, "TMZ just contacted me to tell me Melania Trump is threatening a lawsuit over this video ... I never ever meant this as a bullying video."

The video was posted by someone who says he was diagnosed with autism at age 5, and he says he posted the video because he wanted to stop people for bullying Barron over his "weird behavior."

Fact is ... Barron does not have autism and the video perpetuated the bullying, but the guy behind the video says it will come down and he will issue a retraction and an apology to Melania and Barron.