As I said on your other thread, cats killing frogs is unusual, at least in the experience of other people. Are you sure that cats have been killing frogs. And are you sure that it was cats that pulled up your mesh. Have you actually seen cats interfering with the mesh.
Don't be detered from keeping a pond. Ponds are useful to very many other creatures besides frogs. Frogs only require a pond in the Spring to deposit spawn. Adult frogs prefer to spend most of thier life on land, in long grass, and similar damp places.
There's another thread about cats and frogs here:
Trying to keep cats away from gardens is another subject, and there are numerous threads on that subject. Have a look at these: