The New York Daily News says that the ad, which shows a skinned animal and features an open letter to the singer, had initially been accepted to run in Billboard, the music industry bible.
However, Peta told the newspaper that it suspected the ad had been axed by Billboard after pressure from Lopez's record label Epic, part of Sony, and her publicist Nancy Ryder.
The ad is just one component in a concerted campaign Peta is running to dissuade Lopez from using and wearing fur.
The charity, which advocates an end to all animal testing and vegan diets, has a dedicated website outlining Lopez's involvement with fur and its attempts to get her to change her mind on the subject.
It accuses her of wearing almost every kind of furry animal, from "foxes, who are bludgeoned to death and often skinned alive, to small, gentle chinchillas, who are killed by electrocution or have their delicate necks snapped".
Other celebrities attacked by Peta for their stance on fur including Vogue editor Anna Wintour and supermodel Cindy Crawford.
Seperately, Peta has got in on the April Fool's act with a spoof press release claiming that research has shown that there is a genetic link between small penis size and the thrill of hunting.
It has even gone to the extent of creating a website to back the "research". The charity quotes spokesperson Justin Jest saying: "These findings confirm what we have believed for a long time: Hunters just don't measure up."
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