The spot, produced by JWT New York, shows a woman putting a brick on a purple nappy that resembles P&G's Pampers. The voiceover says: "New Huggies Natural Fit are shaped for babies of the human variety."
P&G filed a false advertising suit, claiming the campaign was similar to one that Kimberly-Clark stopped earlier this year.
It was pulled after the National Advertising Division of Better Business Bureaus ordered the company should modify its claims which it said were not adequately supported.
P&G, the world's biggest advertiser, said it was disappointed with the judge's refusal to issue a restraining order and was reviewing its options.