why the USA government refused to deal with ZAZ-TAVRIA cars.?

Answer 1

Because, as a Russian-made compact, Zaporozhets's crampedness, weak power and total lack of comfort, together with the fact that it was mostly bought by people who could not afford anything better, made no financial or political sense.
Plus, it's unreliable, breaks down often, no supply of parts and... it's"BUTT-UGLY"!

Answer 2

USA has enough imported cars already- we don't want any more- send them to Japan instead