Does Offensive Guard trigger only for monster attacks?

I know, the question might look silly. However, since there are non-monster attacks which trigger the guard and/or Divine Blessing, I am curious whether it triggers for:

• environments (e.g., falling boulders)
• friendlies' attacks
• bombs
• other damage sources which can be guarded

Some digging revealed that the time bomb in the practice area does not apply, but I want to know a more specific answer, especially given that there was a tactic involving self-activation of Enraged Guard using a bomb^*1, and if bombs still apply for Offensive Guard, the same strategy could be applied for e.g., Sword and Shield.

_{*1: For World newcomers, Enraged Guard was a Counter Thrust-like stance which, instead of advancing into a thrust, just granted the hunter a Offensive Guard-like buff. Thus, there was a strategy of just exploding the Large Barrel Bomb and canceling it into Enraged Guard to get the benefit of it.}