The reality is the boys will have consequences every time it happens.
But if these children have behavioural issues, such as poor impulse control, they're clearly not able to manage their behaviour, so the consequences aren't changing their behaviour.
The school won't have enough staff to be with these children all day to ensure they don't lash out at other people.
So they have told the OP's daughter to stay away from the boys and not instigate them in any play as they lash out when she does so.
They can't stop the boys from lashing out if they're going to lash out. They can't keep the children inside all day. The school, I'm sure, has put plenty of interventions in place - the OP can't be told about this, of course - but if these boys are being poorly parented and/or have SEN, then there's only so much these interventions will do. Unless they all have 1-1 TAs who are on a rota to monitor behaviour at playtime, all the school can do is try to keep the children apart.
This isn't about victim blaming or girls having to pussy foot around boys. I am a huge feminist but I am also a practising teacher and am well aware of the challenges around these types of issues. The gender of the children here is irrelevant. We have too many students with SEND in mainstream education and not enough staff, and so we do sometimes (often) have to rely on children understanding that X child is not to be spoken to like Y, Z child is not to be approached at playtime because he/she will hit/bite/scratch, whatever.
The OP has no idea that the school are doing 'nothing'. They may well be. But she needs to go through the complaints procedure to find out.
Calling the police (seriously!), Ofsted, the local council, etc, will achieve nothing here. The school complaints procedure is the first port of call.
At the same time, we all need to be aware of the challenges schools face in an age when too many people are having children without wanting to parent them.