12:18 PM PT -- T.I. and Tiny's attorney, Steve Sadow, tells TMZ ... they "deny in the strongest possible terms these unsubstantiated and baseless allegations."
Sadow adds ... "These allegations are nothing more than the continuation of a sordid shakedown campaign that began on social media." He says the couple "implore everyone not to be taken in by these obvious attempts to manipulate the press and misuse the justice system."
The woman alleging T.I. put a gun to her head and threatened to kill her is now claiming she's getting harassed because the rapper and his wife are smearing her name.
Sabrina Peterson's suing T.I. and Tiny for defamation, because according to new legal docs obtained by TMZ ... she says the couple's public statements and social media posts have smeared her good name ever since she made her allegation against T.I.
Peterson claims she got into an altercation with T.I.'s assistant, and T.I. responded by pointing a gun at her head and saying, "Bitch I'll kill you."
According to the docs ... shortly after making her allegation in January, Tiny retaliated by insulting her and posting a photo of Peterson's 8-year-old son to her millions of followers. Peterson says this exposed her son to "vitriol and danger."
T.I. and Tiny subsequently released statements denying a variety of sexual abuse allegations and other claims against them ... including specifically denying the claims made by Peterson.
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Peterson claims being singled out -- along with allegedly being referenced in T.I.'s 8-minute video where he denies allegations and talks about "evil at play" -- has led to her receiving harassing and threatening messages on Instagram.
She's suing the couple for defamation and infliction of emotional distress. We reached out to T.I. ... no word back yet.