only attack hostle mobs

What is your current AI looking like? If you are using a base entity for the AI it may overwrite your current stuff. Make sure that it's behavior is set to creature and that if you wanted it to attack nothing, to specify that in the AI.

Entity Base is in the top right of the mob AI screen and

behavior is on the second screen at the top.

To make it only attack hostile mobs make sure it attacks nothing first and on the AI screen drag the Attack entities of type and

Select EntityMob

Hope this helps.

Add iron golem Ai .