Hailey Bieber Sends Cease & Desist to TikToker

Hailey and Justin Bieber are continuing to beef with TikToker Julie Theis ... slapping her with a cease-and-desist letter that claims she fabricated her story about their celebrity marriage.

TMZ obtained a copy of the letter written by the Biebers' attorney Evan Spiegel ... who writes that Theis posted "outrageous false, fabricated, and defamatory" statements online about the couple's marriage.

Spiegel also writes Theis uploaded TikTok and Instagram videos of herself claiming that Justin and Hailey's marriage was a great example of an abusive relationship stemming from drug addiction, and calls the allegations "highly damaging."

Furthermore, the cease and desist demands Theis to remove her videos making the allegedly defamatory comments about Hailey and Justin and tells her to her to permanently stop posting content implying the Biebers are in an abusive relationship.

On Tuesday, Theis said on TikTok she received the cease and desist letter from Hailey and Justin's legal team. Theis insisted her social media videos were "clearly opinion-based commentary about relationship dynamics and power."

In a statement, Theis told TMZ ... she's concerned the Biebers are trying to silence her free speech, explaining that she's allowed to express her opinions without legal intimidation.

Theis added ... "It’s extremely elitist to try to silence opinions just because you disagree. Disagreement is not defamation." She also claims she's been receiving death threats since the start of this drama.

We've reached out to Hailey and Justin's team, so far no word back.