I don't think Iran particularly cares about the two state solution or Palestinians in general. They want to be the regional power of the middle east, which means they need to destabilize their rivials (Israel and Saudi Arabia) hence they fund their enemies.

It is no different than what America and the USSR were doing during the cold war just on a smaller scale. Playing cold war games is tricky though because its easy to over extend or let your proxies drag you into a conflicts you don't want. This is what happened to Iran and thus the cold war turned hot.