It may be that Allah will grant love (and friendship) between you and those whom ye (now) hold as enemies. For Allah has power (over all things); And Allah is Oft-Forgiving, Most Merciful. Al-Mumtahanah 60:7 ⧉
As far as justice and fair play are concerned, they will be given to everybody–whether friend or foe. But having friendships with those who are at war with one is not proper.