There are two different cramps you are most likely to expirience. One is on your left hand, from working the clutch, which is something your hand isnt used to. There isnt much you can do about that one, just get used to it.
The right hand, or either wrist, is a case of bad body positioning. You are most likely gripping the bars too tight. Try to maintain a very loose grip. The same you would holding a sponge without squeezing the water out. Your elbows should not be locked. Try to carry your weight with your abs/back muscles, squize the tank with your knees if you gotta. You arms should not carry any weight. Its hard to get used to at first, but once you figure it out, it will be worth it.