XXXTentacion's new music video shows a 6-year-old boy getting strung up by a noose with the rapper himself doing the deed -- a disturbingly powerful image that created serious casting problems ... TMZ has learned.
The "Look at Me" video -- which XXXTentacion conceived and directed -- is centered around police brutality against black citizens, white supremacy and slavery. There's a scene where XXX himself is hanging -- but at one point the music cuts altogether and the scene with 2 young boys begins.
One kid is white and the other black ... and XXX slips the noose around the white child's neck.
Casting director LaShawnna Stanley tells us she went through at least 20 different kids, trying to convince the parents it was a good role with a strong message. One parent even showed up ready to have her son do it, but then backed out saying it was "too dark."
The shoot was pushed back a week before Stanley convinced another mother. She reassured her of the theme and safety measures -- stunt coordinators and a harness.
The video's striking a chord ... it already has over 5 million views after a day.
As for that message -- LaShawnna says XXX wanted viewers to see ... what if it had been white men and boys getting hanged for 150 years in America.