Here’s a tip: You can surround the Christmas tree with a barricade or objects that will prevent the cat from going under the tree and climbing into it, but unfortunately, this will not stop aerial attacks. Try tin foil or double-sided tape, materials cats cannot dig their claws into, around the bottom of the tree. This will work with some cats. You might also try making loud noises when you see your cat getting too close to the tree and this may deter the cat.
For more pet safety tips for the holidays, go to: http://www.petmd.com/cat/seasonal/evr_ct_cats_and_christmas_trees