I noticed (while testing a cloning mod) that you can shoot non-aggressive biters with 'c' BUT even after they are hit, turn aggressive, and call for help to hunt down and kill the player, you can not use 'space' to auto-target the biters. You must continue to use 'c' to fire at the now aggressive biters. Also, by the time I made it back to the biters they were no longer hostile/aggressive, admittedly I was walking to them but I think they should stay hostile for awhile (even if they have already killed the player), perhaps by increasing the pollution value of the chunk by 300-500 when a non-aggressive biter is assaulted?
I believe, I found the problem while solving different bug, someone mentioned you can clone the character with the clone mod.
When you are creating entity, the default force is enemy, so what probably happened is, that the character you created had enemy force.
So creepers didn't attack you, and you couldn't auto attack them, but yes, when you damaged them, they reacted and called for help.