/gamerule doMobInfighting

Gamerule that turns on/off mob in-fighting. When set to false (true by default), mobs will not retaliate when attacked by another mob, aggressive mobs only focusing on the player, neither will they hunt or fight with one another for other reasons besides retaliation

You could also further separate them into mobsRetaliate and mobsHunt (or something like that), for better specificity