Cats are curious creatures and will often find their way onto a Christmas tree. One way to keep cats off the tree is to use a small spray bottle filled with water and spray the cat whenever it tries to climb the tree. You can also try placing citrus scented candles or sprays near the tree, as cats typically dislike the smell. Additionally, you can place aluminum foil or double-sided tape around the base of the tree to make it less appealing for the cat to climb.