It's perfectly normal kitten play and if she was still with her brothers and sisters she would be playing just the same. To try and stop her would be to try and stop a child playing when they are very young. At 7 weeks it can't hurt that much. You will just need to be on your guard. If she shows aggressive behaviour, as she gets used to you it will become less and less. She might be just nervous at the moment. Most people with very young kittens have arms full of scratches.