Are you referring to the West Bank or Gaza? Because they’re both not part of Israel. Palestinians in Israel absolutely vote and have their own representatives in government.
If Israel were really committed to democratic ideals, they would either make all Palestinians equal citizens of the state (currently Israel, which would presumably be renamed “Palestine” the next day), or, more realistically, they would allow the Palestinian Territories to become an independent state, rather than keeping them permanently occupied and subject to Israeli military law.
on the other hand, the situation in so-called palestinian territories is completely different. Gaza strip was officially annexed by Egypt, West Bank was officially annexed by Jordan - so the official government would be these countries, and if we're talking about Apartheid, then it would be committed by these countries.