Firstly, I don't think forgiveness means complete absolution from justice (just to clarify some definitions). I think it means absolution from any form of revenge, redemptive violence, punishment for its own sake, etc. We can forgive someone for a violent act, but if they are likely to continue their violence that doesn't mean allowing them to freely do so. We can forgive someone for a sin, but if they do not seek reconciliation nor repent, then (I think) justice can come in the form of protection and rehabilitation.
Protective and even rehabilitative measures may be perceived as punishment, but can be done out of love rather than hate (though this can be a very difficult distinction when emotional extremes are at play). Imprisonment, isolation, excommunication where there is no sign of repentance—sometimes it can be better to end relationships or leave communities where our own failings mean reconciliation is impossible, unwanted, or risks much more serious damage than going separate ways, for example.
In such cases, there may be forgiveness along-side what is perceived to be punishment. But I would argue that only if said 'punishment' is purely for protection and rehabilitation; not when the punishment is purely for its own sake.
I don't think we've truly forgiven someone if we're holding out for God (or society) to punish them. If we're holding onto the idea that they will be punished for their actions, that some justice remains to be served beyond protection and reconciliation/rehabilitation, then what have we really forgiven? It's probably better than nothing; a tool to alleviate one's own desire to carry out acts of revenge or punitive redemption, but if we still wish punishment and suffering on a person then we do not love them, we have not forgiven them.
I suspect some will take issue with my understanding, because of e.g. 'turning the other cheek', but my understanding of that concept is a shaming of the oppressor as a way of non-violent resistance, an alternate way of confronting the powerful, rather than completely passive, immediate and unquestioning forgiveness (which is not in itself resistive, does not challenge an unjust society, nor speak truth to power).