I've also been told that if you take tape and put it sticky side out on the outside of the tank(making it's nowhere near your snake). The cat will not like sticking to it, and may start avoiding in the future.

Or, if you have a really stubborn cat like I do, and you have the space, put them behind closed doors. My cat thinks every other animal I own is a toy. The doors to the herp room and the inver room are always closed.