When my sister's cat EB was a kitten she used to play like that with my cat Saxony, who was at least 4 times her size.
At first I was worried, because it looked like they were both being really rough on each other, so I would break it up. As soon as my back was turned, EB would be jumping on Saxony and biting him, and he would do the same thing.
Only once did EB cry out in pain, and as soon as she did Saxony let her go.