Neo,
What kind of pain is it? Is it a muscle pain or a bone pain?
What kind of landings are you doing? Are you doing a roll, or just landing on all fours?
Also, how old are you and in what physical condition? Are you in good shape?
I had some muscle pain in my back at the beginning too. It wasn't so much as pain, but more like I was aware something was going on when I did certain movements involving my waist. I resolved this by stretching my back. The stretch that I found worked this well was this:
Sit on the floor with both legs together and straight out. Try to touch your toes. Keep trying for about 2 minutes.
I do this every day when I get up in the morning, together with other stretching movements, as I am sipping on my coffee. Sometimes, when I have time, I do this at night too.
This will not only stretch your hamstrings, but will stretch your glutes and lower back as well.
After a while, maybe a week or two, I had no more lower back issues.
If this isn't what's happening with you, answer the questions above, maybe I can help out.