Charlie Sheen -- Private School A-Holes Are HARASSING My Ex-Wife

Charlie Sheen's war against an L.A. private school has turned personal ... Charlie says his ex-wife Denise Richards has now been targeted by the school's "spineless" supporters, who have embarked on a campaign to bully her and their children.

Charlie posted the latest tirade on his Twitter account, writing, "Here's why people suck; a group of mindless Viewpoint [School] supporting doosh-bagz have targeted [Denise] and the girls with 'bullying tactics' as a response to my call to arms."

Sources close to Charlie tell us, Charlie believes the "doosh bagz" in question are connected with families at L.A.'s expensive Viewpoint School, which Charlie publicly accused of condoning bullying ... after his 9-year-old daughter Sam was allegedly teased into leaving the school. The school insisted it took appropriate action.

We're told the "doosh bagz" live near Denise ... and have been harassing her at home. So far, it's unclear what they're accused of doing.

As for his new rant -- Charlie continued, writing, "Leave them alone. This is not a threat but a promise that justice will be served. I'm not hiding. You are. Show yourselves you spineless cowards. Oh that's right; cockroaches scatter in the light."