In Islam violence is not prohibited it is conditional. With the condition being that it is to be used against an aggressor or combatant. Which is someone who initiates fighting against a believer.

Qur’an 2:190 Fight in the way of Allah THOSE WHO FIGHT YOU but do not transgress limits. Indeed. Allah does not like transgressors.
Arabic:وَقَاتِلُوا فِي سَبِيلِ اللَّهِ الَّذِينَ يُقَاتِلُونَكُمْ وَلَا تَعْتَدُوا إِنَّ اللَّهَ لَا يُحِبُّ الْمُعْتَدِينَ
(emphasis added)

It should be noted that someone who initiates fighting against a believer puts him or her on the DEFENSE. The intent  therefore, should always be to DEFEND ones-self or another. Which is the opposite of an unjust use of violence.