--- a/net/minecraft/world/entity/animal/EntityIronGolem.java
+++ b/net/minecraft/world/entity/animal/EntityIronGolem.java
@@ -105,7 +105,7 @@
     @Override
     protected void doPush(Entity entity) {
         if (entity instanceof IMonster && !(entity instanceof EntityCreeper) && this.getRandom().nextInt(20) == 0) {
-            this.setTarget((EntityLiving) entity);
+            this.setTarget((EntityLiving) entity, org.bukkit.event.entity.EntityTargetLivingEntityEvent.TargetReason.COLLISION, true); // CraftBukkit - set reason
         }
 
         super.doPush(entity);