Tasha Marbury says she's being harassed online by a woman obsessed with her husband -- and now the "Basketball Wives" star has filed a police report against her.

Tasha -- who's married to former NBA star Stephon Marbury -- filed the report with the Harrison P.D. in NY on January 31 against a woman going by the name of Monet Merchand.

Tasha claims Merchand has been negatively blogging and tweeting about her. Tasha claims Merchand is harassing her non-stop on social media ... tweeting things like "@TashaMarbury is an insecure hoe" and "You are less 'worth' than a burnt out light bulb & you will forever live in shame."

Merchand has made claims on social media that she had an affair with Stephon, but sources tell us Stephon claims to have NEVER met Merchand.