Dontavious Jackson -- a former star linebacker at Florida State -- says he was called a "f***ing n****r" during an altercation on a flight Wednesday ... and then he claims he was nearly arrested over it all.
Jackson spelled out the disturbing story on his Twitter page late Wednesday night ... saying he was on a United flight when a "racist family" began harassing him.
Jackson claims he was called racial slurs ... but says "flight attendants just let it happen!"
"Unacceptable!!" Jackson wrote of the incident.
But, Dontavious -- who played in 43 games for the Seminoles from 2016 through 2019 -- says when cops arrived to investigate the altercation in Miami, they nearly arrested HIM over it all.