First, make sure the tree is in a safe spot away from windows or other areas where the cat can get to it. Make sure the tree is well anchored so it won't tip over easily. Use a spray bottle of water to discourage the cat from approaching the tree, or place aluminum foil around the bottom of the tree to make it less attractive to climb. You can also use citrus scents or sticky tape on the tree to deter the cat. Finally, provide plenty of alternative toys and activities to keep the cat occupied.