Give it a spot where it can dig, maybe a big wooden box - 3' x 5' and 3' or 4' deep filled with compacted soil and bury that in the ground. Then put Chicken wire (or 1/4" wire) on the ground where you don't want it to dig. Not a cheap solution, but if you don't want to cage it...

On the other hand you could buy/make a good sized cage and hutch and the rabbit could come out to play with supervision. Just my 2 cents...