Secretary of State Mike Pompeo accused Tehran of using Iran deal funds to back the Lebanese Shiite Muslim Hezbollah, as well as the jihadi Sunni Muslim groups.
A White House spokesman told skeptical reporters that blaming Israel for Palestinian deaths was "a propaganda attempt" by Hamas.
Fadi al-Batsh was allegedly part of an overseas Hamas operation researching new weapons technology.
Fadi Mohammad al-Batsh, 35, was shot dead by motorcycle gunmen in a suburb of Kuala Lumpur.
His party, Fatah, has called the blast an assassination attempt by political rival Hamas.
Rabbi Raziel Shevach was killed in a drive-by shooting near his settlement on Tuesday.
The jihadi group threatened to attack the “pillars of tyranny that prop up” the Palestinian faction.
Syria, Iran and Hezbollah's so-called axis of resistance may have found itself new Palestinian and Iraqi partners opposed to Israel and the U.S.
Rockets were already fired at Israel from Gaza, but Hamas was seeking a popular uprising.
The militant group has indicated that it does not want an escalation with Israel.
Iran's powerful allies prepared responses to Trump's Jerusalem speech.
"Any decision to move its embassy there would be "a flagrant attack on the city by the American administration," Hamas said.
Yahya Sinwar, a hardliner who was elected head of Hamas in Gaza in February this year, made the comments at a meeting of Palestinian youth.
Thousands of camouflage army boots were to make their way to Hamas's military wing, Israel says.
Fatah says it is ready for reconciliation with its Palestinian rival.
Shin Bet chief says Palestinian militants are deepening connection with the Iran’s “Shiite axis.”
Tehran fell out with Hamas when the Palestinian Islamist movement turned its back on Syrian leader Bashar al-Assad in 2012.
The Israeli army has revealed details of a wall in the planning since 2014.
In a video, children appear to be dressed as militants, re-enacting recent clashes in the contested city.
The U.S. must follow Arab nations and take a stand against Qatar for hosting and funding terrorists.
The militant group hanged two men and killed a third by firing squad on Thursday.