Such deadly attacks on civilians were against international law and constituted "a war crime," it said.
It urged Palestinian armed groups to end all direct attacks on Israeli civilians and ensure everything was done to also protect Palestinian civilians inside Gaza from the effects of those attacks.
The 50-day war claimed the lives of some 2,200 people in Gaza, most of them civilians, and 73 on the Israeli side, most of them soldiers.
It referred to one particular incident on July 28 in which 13 people were killed in deadly blast inside the beachside Shati refugee camp in Gaza City.
At the time, Palestinian witnesses blamed the attack on an Israeli F-16 warplane, but the army denied firing on the camp, accusing militants of misfiring their own rockets.
"In the deadliest incident believed to have been caused by a Palestinian armed group during the conflict, 13 Palestinian civilians -- 11 of them children -- were killed when a projectile exploded next to a supermarket in the crowded al-Shati refugee camp," the report said.
Figures released by the Israeli army just days after the war ended on August 26 showed that Gaza militants fired 4,591 projectiles at Israel.
Of that number, 3,659 struck Israeli territory and 735 were intercepted by the Iron Dome air defence system, leaving another 197 which fell short and landed inside the coastal enclave.
Militant groups used unguided projectiles which were "inherently indiscriminate," it said: "Using such weapons is prohibited under international law and their use constitutes a war crime."
