The ad includes comments from Capitol police officers recounting the violence on the day of the insurrection
The group that produced the ad, MeidasTouch, sought to run the ad on Sunday, but Fox declined.
One of the group’s co-founders, Ben Meiselas, said they were informed on Friday by phone that the ad would not be run on the network.
Mr Meiselas claimed he was not given a reason for the refusal by Fox News.
“We couldn’t have fathomed in our wildest imaginations that even Fox News would reject an ad that simply condemns the insurrection, and condemns people who support the insurrection,” he told the LA Times.
The group claimed that Fox had never rejected one of their adverts before.
The ad is a montage of images of the Capitol riot cut over and with interviews from Capitol police officers who were attacked that day, recalling the brutality of the fighting and the sadness they felt at being attacked by their fellow citizens.
In one clip, DC Metropolitan Police Officer Michael Fanone expresses his frustration with Republican lawmakers who have attempted to sweep the riot under the rug.
“It’s been very difficult seeing elected officials and other individuals whitewash the events of that day or downplay what happened,” Mr Fanone says in the video.
The ad also features the testimony of Capitol police Captain Carneysha Mendoza during a hearing by the Senate Homeland Security and Governmental Affairs & Senate Rules and Administration.
“We made a $184,854 TV buy with this ad on Fox News this week. Fox News just denied airing our ad. Retweet and get it out in every corner of the country,” MeidasTouch said on Twitter.
The ad ends with a title that reads “The GOP betrayed America. We will never forget.”
A Fox News spokesperson said the claim that it had not turned down previous ads from the PAC was incorrect.