Can't post because level not high enough?

[VisRalis]

Actually, if the target is an enemy, it will self-cast cure and never make it to the second line.

If you macro it, actually you have to add a new line /ac Cure <me> for it to self-cast cure in case first two conditions are not met.

For Cure <t> you will be targeting a PC/NPC (cure won't heal enemies so it'll skip to next line)
If you're targeting an enemy/boss, <tt> will target whoever the boss is targeting (tank normally)
If you're not targeting anything, then the final line <me> will activate healing yourself, as would Cure normally do outside of macro.

So its working as intended