The pets, along with their owners, were due to attend this weekend's event to endorse a charity's effort to find new shelters for retired police canines.
On its Facebook page, the Spanish non-profit organization Heroes de 4 Patas (Heroes on four legs) immediately condemned the decision to ban the dogs as "very bad," and posted a message on behalf of one of the pets.
"I do not understand why some people don't like my presence, it may be because I am a former retired policeman, because I am Galician [Spanish] and Catalan, or because of the uniform of my former colleague who taught me everything I know. I do not understand what's happening in Catalonia, I'm just a dog," the post said.
The secession of Catalonia from Spain were backed by 90.18 percent, or more than 2.28 million voters, with a turnout exceeding 43 percent. The Spanish government refused to recognize the referendum's official results.