How to specify the level of a hierarchy in exposed filter ?

I have a problem/question to resolve.

Is it possible to specify a vocabulary hierarchy level in a taxonomy exposed filter ? This, in order to limit the terms listed in the filter, only to the level i need.

I mean, i have a regional vocabulary with a 3-level hierarchy structure:
-countries (as parent terms)
-regions (level1 terms)
-cities (level2 terms)

What I need is the exposed filter LISTING ONLY the the cities, Is this possible ?

Thanks!