Cats are curious creatures, and they may see the Christmas tree as a new toy or a challenge to climb. To deter cats from the Christmas tree, there are several things you can try. First, make sure the tree is secured and stable so it can't be easily knocked over. Second, use scents or sounds to discourage the cats, such as spraying the tree with a citrus-scented spray or using a motion sensor to set off a noise when the cat approaches the tree. Finally, provide an alternative activity for the cats, like a scratching post or a cat tower.