In Surah Yaseen it is mentioned that وَمَا عَلَّمْنَاهُ الشِّعْرَ وَمَا يَنبَغِي لَهُ

"And We did not give Prophet Muhammad (ﷺ), knowledge of poetry, nor is it befitting for him." [1] However, I find many war poems attributed to Prophet (ﷺ) as mentioned in book of Seerah by Mubarkpuri (Urdu version) and also mentioned in fatwa [2] that during Uhud and Ahzaab and other different times of Prophet (ﷺ) life he said some verses / poems like: اللهم ان العيش عيش الاخرة

How we can reconcile Qur'anic verse regarding knowledge of poetry (in Surah Yaseen) and these poems.?

The mentioning of the Prophet (ﷺ) as not being given knowledge of poetry is in reference to the Qur'an not being the poetic work of a man. It sanctifies the speech of Allah and rules out any consideration that a human being composed it.

Secondly, the Prophet (ﷺ) made varying statements in his life that were poetic in its linguistic structure, or poetic through cultural practice but did not recite poetry explicitly.

We do not refer to these statements as actual poems of the Prophet (ﷺ) as this could be interpreted as him being considered a poet.

References:

[1] [Qur’an 36:69]

[2] http://islamqa.info/ar/174568