Taylor Swift to One Direction — ‘SHUT THE F**K UP!’

Taylor Swift doesn”t just write breakup songs about her ex-boyfriends … she talks SMACK about them during award shows … and last night, she got caught. On camera.

It happened when One Direction took the stage to present a Moon Man at the MTV VMAs for Best Pop Video.

FYI — Taylor used to date Harry Styles (they broke up in January) … but apparently, she”s still harboring some resentment — “cause as the band rambled on, the camera cut to Swift … who leaned over to Selena Gomez and mouthed the words, “SHUT. THE. F**K. UP.”

A bitter Taylor Swift We”re shocked.