This method can be used to make both, disable PvP and make hostile mobs passive.
In java, we can create teams, and we can configure friendly fire to make people of that team unable to attack each other. This also works for mobs. In this example we are going to make zombies passive to players.
# in chat / load function
team add Friendly
team join @a friendly
# tick function / command blocks
team join @e[team=!friendly,type=zombie] friendly
If you can’t use the /team command (because you are using it for another thing or you are in bedrock) you can use effects. If we give resistance level 5 or higher the entity will be invulnerable to all damages except the /kill command. Weakness is recommended to avoid the player or mob cause knockback.
[!NOTE] The entity will be invulnerable even to other damage sources, such as fall damage, entity cramming or attacks that aren’t caused by the player.
In this example we are going to make all zombies unable to attack the player for one minute
/effect give @e[type=zombie] weakness 60 127 true
And if we want the player to be unable to attack the zombie
/effect give @a weakness 60 127
[!NOTE] You can still attack the player/entity if you have the sharpness enchantment, that’s why we use resistance.
This method wont work to dissable PvP, it will only prevent the entity attacking the player.
It is unclear whether this is a bug, but it is shown in this Reddit post that constantly using /item on the mob will mess up the AI and will thus prevent it from attacking the player.
[!NOTE] This does not work in Bedrock
# Java syntax
/item replace entity @e[type=skeleton] armor.head with iron_helmet
You can modify the follow range attribute of some mobs so they can’t find you. In bedrock you can use the invisibility effect to reduce this range, use mob heads or you change a mobs behavior file to change their follow range that way.
This method will not make hostile mobs passive but it will prevent players from attacking other entities or players.
If it is for only one mob you can add an interaction entity that constantly teleports to the mob or rides it and the player will attack the interaction instead of the mob, this will make the mob unkillable with attacks
Important things to keep in mind when using this method:
In java edition there are 2 attributes related to the range that players can interact with the world. we can reduce this range and set it to -4.5 to make them unable to interact with other entities.
[!NOTE] This will affect right click too so they won’t be able to trade with villagers for example.