Apologies for any duplication, keywords used for search: Blaze attacks creative, Blaze, Blazes Nether, Blaze Creative, Mobs attack creative.
Usually, in creative, when you hit a mob they will not attack you. However, blazes attack back when you hit them. Example; if you hit the blaze for the first time the blaze will become en-flamed. If you hit them again they will fire a fire charge at the player you have to hit them repeatedly to reproduce. When the player doesn't hit the blaze, they blaze won't attack if they have already been hit.
Steps to reproduce
1. Go to the Nether biome and find a blaze (or spawn one in)
2. Attack the blaze repeatedly (I did this with no weapon (melee))
As I have stated, you need to hit the blaze a couple of times. I am unsure if this affects the later snapshots. I know there was an issue that opened with the similar bug and was fixed however this is a new bug and hasn't been fixed.
2014-02-07_00.06.31 - Normal Blaze
2014-02-07_00.06.33 - Blaze in fight mode
2014-02-07_00.06.43 - Blaze firing 'fire charge'