I dont know if there is an easy way for it but this should work, translations will be in ´(´ ´)´:
Go 1 point under Attack for: Поиск цели(ignore target)
Then go to the second tab: фильтр(filter)
Then click on the button: Видимые NPC(seen NPCs)
Keep the monsters you dont want to attack ticked and the monsters you want to attack you untick. Then click on: Добавит(add) its on the right if I remember right.
Now select one of the monster in the list and tick: Не атаковатъ(dont attack) . It is almost on the bottom of the window.
Then click on: Все так же(everyone the same) . Now all monsters you ticked should be marked with Не атаковатъ.
you are done.