I'll be a little more helpful since the problem is such a basic fix/change. Basically, you're casting a healing spell, much like greater healing, that is only targetting your pet. This is applying the same threat generation for casting a healing spell.
You're going to want to find the following function
Code:
int32 Mob::CheckHealAggroAmount(uint16 spell_id, Mob *target, uint32 heal_possible)
and apply this basic change
Code:
if (spells[spell_id].targettype == ST_Pet)
return 0;
Now, this is going to make *any* spell that heals with the target type pet to generate zero aggro. I'm assuming this is what you want with the information you provided since I have no idea how live works. Healing the pet with targetted healing spells will generate aggro normally.
(With that said I vaguely remember adds attempting to kill me back in the day when I tried healing my pet. So in that case, you'll want to create a reduced threat formula.)