Charlie Sheen -- School Lashes Back at Dog Crap Plot

Charlie Sheen's rant about an expensive L.A. private school really pissed off the school's administrators ... and now they're returning fire.

You'll recall, Sheen ripped the school on Twitter last night, claiming it did nothing after another student allegedly bullied and tormented his 9-year-old daughter Sam ... teasing her mercilessly about her skin, her looks, her hair, and even Charlie getting fired from "Two and a Half Men."

Sheen pulled Sam out of the school last May, and for some reason, unloaded on Viewpoint last night, urging his fans to deliver dog poop and other gross things to the school and smear them over the campus.

Now, Viewpoint is responding ... telling parents via Twitter, "Viewpoint School’s highest priority is the safety, security and education of our students."

The rep says, "The parent [cough cough...Charlie] of a former Viewpoint School student who has not attended Viewpoint School since March, 2012 has made certain accusations in the media ... Our administrators addressed the issue appropriately [last year]."

The rep adds, "Our School takes accusations of bullying very seriously. For over 50 years, Viewpoint School has provided a safe and nurturing environment for our students to thrive, and we will continue to do so.