Improved Natural Attack and the monk

[wolfen]

Now I know most will say that this of course does not work as is stated in the rules for the INA feat "Choose one of the creature’s natural attack forms.The damage for this natural attack increases by one step on
the following list, as if the creature’s size had increased by
one category." (I copy and pasted this from the book exact wording).
But now when you look under the monks description for Unarmed Strike it states "A monk’s unarmed strike is treated as both a manufactured weapon and a natural weapon for the purpose of spells and effects that enhance or improve either manufactured weapons or natural weapons."

Now with this being said I understand that the feat is not considered a spell as is obvious, but as is stated his fist does count as a natural weapon so would not the feat count?

Please give detailed reason as to yes or no preferably with citation from the book to back your claim not just because I said so.

[Weren Wu Jen]

That's pre-errata. From the PRD:

Improved Natural Attack

Attacks made by one of this creature's natural attacks leave vicious wounds.

Prerequisite: Natural weapon, base attack bonus +4.

Benefit: Choose one of the creature's natural attack forms (not an unarmed strike). The damage for this natural attack increases by one step on the following list, as if the creature's size had increased by one category. Damage dice increase as follows: 1d2, 1d3, 1d4, 1d6, 1d8, 2d6, 3d6, 4d6, 6d6, 8d6, 12d6.

(Emphasis mine.)

Sorry. :(

[Are]

The current version of the Bestiary says the following under the Improved Natural Attack feat (first sentence):

PRD wrote:

Choose one of the creature's natural attack forms (not an unarmed strike).

So that's the reason it doesn't work.

It did work in 3.5, and my opinion is that it should still work, but the Pathfinder developers don't think it should work, and have added a clause specifically to disallow it.