Zombies retaliate when only hitten in Creative Mode

In Survival,when skeleton shoots zombie,he fights normally until skeleton or he dies,but in Creative,skeleton can provoke zombie only,if player hit him and zombie attacks skeleton only for few seconds.

How to reproduce:
1.Make skeleton hit Zombie in Survival Mode.
2.Make skeleton hit Zombie in Creative Mode.
3.Now try to hit zombie yourself in Creative Mode.
4.Make again skeleton hit Zombie in Creative Mode.