Rabbit? or Mole? --- You need to create a wire fence dug dip into the ground to prevent them entering the area. The fence wire must be layed down bent in an L shaped so that it won't be easy for the creatures to simply dig a hole to bypass the fence.

Set traps as well.

Use scent to scare off the creatures - I believe I've spotted on the web, some fox scented chemicals. the idea is that these creatures would think there is a predator in the area and thus should be scared off.

Use some motion activated sprinkler or sound system. - I think lee valley tools has some of these gadgets.

Fool them by laying down rubber snakes.

The thing with these creatures are that they are smart and so you will need to vary your approach every now and then.

Good luck.

Not my fence. I am in a community garden so laying down a motion activated sprinkler system is not feasible. There is only one tap that everyone has to share. I will look into the rubber snake thing and scents. Thanks!