What is the ruling on intentionally killing a non-Muslim due to disputes, and is the killer only required to pay blood money?

It is not permissible to kill a soul unjustly, whether it be Muslim or disbeliever. A severe warning has been issued against anyone who wrongs or kills a mu'ahid (a non-Muslim living under Muslim protection by treaty) or a dhimmī (a non-Muslim subject living in a Muslim state). The Prophet, peace and blessings be upon him, said: "Beware! Whoever wrongs a mu'ahid, or diminishes his right, or burdens him beyond his capacity, or takes anything from him without his willing consent, then I shall be his adversary on the Day of Judgment." He also said: "Whoever kills a mu'ahid will not smell the scent of Paradise." As for qisas (retaliation in kind), the majority of scholars hold that a Muslim is not killed for a disbeliever, but this does not mean that killing him is permissible. Indeed, killing a mu'ahid or a dhimmī exposes one to a severe warning.