From further reading, it appears the relationship between Hamas and Iran is complicated and on-again off-again. In 2012 Hamas was cracking down on Sunnis that converted to Shia. Later Hamas was receiving funding from Iran. 

 Hamas main benefactor has always been the Isreali political executive branch. Harder to persue a strategy of tensions with a smart moderate opponent. 

 How would Isreali politics work if every 6 months a settler maimed a young Haarzt reader who'd moved to Ramallah for tax breaks and just happened to be chatting to a neighbour in Arabic the wrong time?