Encourage all types of friendships. The person you are trying to direct her away from could be her best friend. Let your daughter see potential friends for what they are and choose her own friends. You will not be there in K and elementary school through grade 12 to negotiate her friendships. She is learning now.
What your daughter is experiencing is normal 4 yr old behavior and how they are learning to be friends. Some friends are not going to be all sweet and nice and others can be a little more difficult because they are ALL learning.
Example... when our daughter was younger, she did socialize with those who were sweet as pie and some who weren't so sweet. However, when children are together and work on these social relationships, it is like rough rocks that keep rubbing against each other that do eventually become smooth.
The "becoming smooth" process is not typically bullying behavior. What you have described is not bullying behavior. You have described normal 4 yr olds learning how to get along and it is not always easy.
Please don't use the term bully so loosely as it is so over used and when it is over used the way it is, people will stop responding and then someone who is truly bullied will not get the help needed.
It is like crying wolf all the time and then it is too late when the real wolf is there.
Best wishes..
ETA: Per your SWH, I am sorry but I still disagree with your theory that this is bullying. Your daughter is in a social situation learning how to deal with all kinds of children and someday it will mean dealing with adults.
I feel sorry for your daughter that you have already labeled her as a victim in preschool. Please don't do that to her. She needs you to be her mentor to guide her through situations that are not so much fun so she can grow into a strong woman vs being the poor pitiful me. You don't run to the principal because someone said something mean to your child. IF this other child is so bad, then the school will deal with her but you focus on your daughter growing up to be a strong person. You can help her be strong or you can label her victim and she'll play that role all of her life and not get very far.