Vetar

[ROBINDESBOIS]

How can I say in English?
Le vetaré mi habitación ( context. Talking about a cat so that it doesn´t leave any of its hairs on my clothes)

I´ll veto my room to it/him. I want to use the word veto, not ban or prohibit.

[Rusty]

I'll veto access to my room by him (the cat).
I'll veto his (the cat's) rights to my room.
Permission to my room by him (the cat) will be vetoed.

[pjt33]

I want to use the word veto, not ban or prohibit.
It would be much more natural to use ban.

[poli]

You should also note that veto is a word often used in official capacities. A proposal was vetoed by the senate, for example.

Vetoing a cat's access seems comical, but if you propose to allow pets to the co-op board, they may veto it.

Under ordinary circumstances, you will more likely hear, I won't allow the cat in my room.

I just noticed PJT33's response which I completely agree with.

[ROBINDESBOIS]

I know but I wanted to use veto, metaphorically.

[Rusty]

One of the meanings of 'veto' fits what you intended to say, hence my examples. However, as others have said, 'veto' isn't commonly used to portray that idea.

[Sancho Panther]

In UK you'd say "I'll stop that cat from coming into my room".

[ROBINDESBOIS]

Well, I just wanted to know the use of Veto, in Spanish is not very usual either, but people would understand it.