The group, entitled Down With Disney's Treatment of Franchises and its Fanboys (DWDTFF), was planning to spam the film with negative reviews.
Facebook has now closed the group's page down and Rotten Tomatoes says it will ban the group's members and delete their comments.
"We at Rotten Tomatoes are proud to have become a platform for passionate fans to debate and discuss entertainment and we take that responsibility seriously," Rotten Tomatoes says in a statement.
"While we respect our fans' diverse opinions, we do not condone hate speech. Our team of security, network and social experts continue to closely monitor our platforms and any users who engage in such activities will be blocked from our site and their comments removed as quickly as possible."
DWDTFF previously boasted about bringing down the Rotten Tomatoes score of Star Wars: The Last Jedi.
In an interview with Inverse, the DWDTFF leader said Black Panther was an attempt "to shove SJW [social justice warrior] messages down our throats" and added that "minorities... should stay that way".
The group propagates conspiracy theories about Disney paying critics for good reviews and believes bad media coverage of DCEU films, such as Justice League and Batman V Superman, is falsified.
Black Panther is the first Marvel film to feature a black lead star, a black director and a mostly black cast.
It's set for release in New Zealand on February 14.