The bulk of anti-bullying activity consists of things that cannot be done by the police. However, there are things that the police can do to reduce bullying in schools.
For the most part, these are things that could be done at the high school level. The placement of what are often called "resource officers" in the school itself can be a help. Such officers can, at the very least, work to ensure that bullying does not take a physical form. They can ensure that any assaults will be dealt with and, thereby, they can hope to deter such violence.
Outside of that, most steps that can be taken against bullying have to be done through education rather than through law enforcement.