@Occhi_Di_Gatto criminals/civilians are allowed to help each other. Whether they are friends or not does not matter:
If you are chasing a criminal, any civilian has the right to attack you in order to defend the criminal.
What isn't allowed is him attacking you AFTER you arrest/kill the suspect you were chasing because then he wasn't defending anyone and it'd simply be cophunt. However your description of the situation and your 2nd attached image both show that you were still chasing the criminal when xxzc1g attacked/rammed you, which means xxzc1g did nothing wrong.