The baby was not injured in the Sunday incident.
Sgt. Pete Simpson, a Portland Police Bureau spokesman, said officers responded to a 911 call that evening from a couple who had locked themselves in their bedroom with the baby and their dog after the cat attacked the child.
Simpson said the 911 operator could hear the cat screeching in the background as the couple awaited help.
Officers used a dog snare to capture the cat and placed it in a crate.
Simpson said the owners told the dispatcher the cat has a history of violence. He said the cat remained with its owners.