How to keep our 4 month old kitten from attacking out 3 year old

We've had Simon since September and before he was so sweet and gentle with her. Now he chases her around biting and scratching her. She likes to lay on the floor and color, he jumps on top of her head, biting and clawing. 

I really don't want to get rid of him but he always wants to attach himself to her face! Please help!!

Does the 3 yr old grab him too hard or pull on him?  Is she rough with him?  Toddlers and kittens often do not mix because toddlers do not have the coordination or control to not be rough.  Kittens are fragile and they don't know how to get away so their only defense is to attack.  It could also be his age.  He is at the ornery stage of life.  He'll calm down in a couple of months. 

You can make a safe room or are for him.  Tell your toddler that when kitty is in there, he is to be left alone because it is a time out.  You are not punishing him but this is a good idea for any pet with toddlers in the home.  Until your toddler can control herself and learns how to pet and handle him and until he is big enough to get away from her himself, he needs to be supervised and kept at a pretty good distance and monitored while she is handling him.  This means, you hold him while she pets him gently.  That way, you are in control.  Then, at times you cannot do this, he is in his room.  Make sure all his stuff is there and he is comfortable and happy in there.