Karrueche Tran is blaming BET for the fact she ripped Beyonce and Jay Z's little girl with a harsh joke about her hair while hosting "106 & Park."
The joke took a shot at Blue Ivy's hairdo and no one ever combing it -- but it quickly blew up in Karreuche's face when incensed Bey and Jay fans unleashed a vicious social media attack on her.
A source close to Chris Brown's GF tells TMZ ... she read the joke cold off a teleprompter -- it was in a script that had been changed by producers at the last-minute -- and she never saw it beforehand.
We're told ... it was a live show and KT had no choice but to read what was on the prompter. Afterward, she and her manager went nuclear because they also thought the joke -- about a 2-year-old -- was mean-spirited and in poor taste.
Karrueche tells TMZ she actually admires Blue's 'do, saying ... "I love that Blue is able to wear her natural hair." She added she would never disrespect Beyonce and Blue Ivy.
BET President Stephen Hill also apologized, saying he reached out to Beyonce and Jay Z ... and has "taken punitive actions" with the producers responsible for putting Karrueche in that position.