I am talking with my colleague at work and I said "this man" told me, and I referred to the third highest colleague in functional class is with us. Is "this man" is not polite phrase?
No, it is not.
This man will typically be understood as disparaging in all cases where the person's name or title are known.
So if you are talking about a specific person, please use
- either the name
Mr. Smith told me...
or first name
John told me...
depending on what is common in your team,
- or the function/title or any other kind of description, especially if you want to emphazise the role or the name will not be immediately recognized or you don't know it
The new collegue from Argentina told me...
The man at the reception told me...
If everyone knows whom you are talking about, you may of course use the pronoun in the gender-appropriate form:
He told me... or She told me...
The only instance where this / that man / woman / ... is appropriate is if you need a demonstrative to point out a specific person who you can not "name properly" like in the examples above, often used to distinguish between two or more:
This man here has brought an umbrella, but that man over there apparently didn't.
Note that at least in formal or semi-formal settings the terms "man" or "woman" would often be replaced by "gentleman" or "lady".