Chris Brown says he's been SET UP -- claiming one of his neighbors scratched the initials "C.B." into an elevator at his Hollywood condo building in an effort to make the singer look like a "reckless" punk.
TMZ broke the story ... Brown's neighbors HATE HIS GUTS and have complained to the building manager about noise, parking violations and a mysterious case of elevator vandalism ever since the singer moved in a few months ago.
But now, Brown has FIRED BACK on his Twitter page -- saying HE is the real victim -- "My neighbor carves my name in our elevator to incriminate me so it looks like I'm a reckless 22 your old (sic)."
As for the TMZ photos showing Brown parking in handicapped spaces, Brown explained, "My parking spaces in my building that were assigned to me when I [bought] this crib are painted over with handicap and no Parking signs."
He added, "A person should be able to live in his or her own company of their house! I'm barely home so these stories and accusations are so childish!"