In a new report, Amnesty International details eight instances in which Israeli forces attacked homes in Gaza "without warning", killing "at least 104 civilians including 62 children".
Israel rejected the rights group's findings, saying it produced "no evidence" to back up its claims in what was effectively "a propaganda tool for Hamas".
"The report reveals a pattern of frequent Israeli attacks using large aerial bombs to level civilian homes, sometimes killingentire families," Amnesty said.
It added that while possible military targets were identified in some cases, "the devastation to civilian lives was clearly disproportionate."
The report charged that when it appeared to have failed to identify "any possible military target" in a Gaza residential building, Israel may have "directly and deliberately targeted civilians or civilian objects, which would constitute war crimes."
"The report exposes a pattern of attacks on civilian homes by Israeli forces which have shown a shocking disregard for the lives of Palestinian civilians."
Philip Luther, Amnesty's director for the Middle East and North Africa said "civilians were given no warning and had no chance to flee," said.
Amnesty said "Palestinian armed groups also committed war crimes, firing thousands of indiscriminate rockets into Israel killing six civilians including one child".
The group said it had to conduct research for the report remotely as Israel denied it and other watchdogs access to Gaza.
Amnesty called on Israel and the Palestinians to "accede to the Rome Statute and grant the ICC (International Criminal Court) the authority to investigate crimes committed in Israel and the Occupied Palestinian Territories".
It also called for cooperation with the UN Human Rights Committee, which last month urged Israel to ensure an independent and impartial investigation to the Gaza war.
Israel said Amnesty had provided "no evidence" to back up its claims, while ignoring "documented war crimes perpetrated by Hamas.
It cited "the use of human shields, as well as ammunition storage and firing at Israeli civilian population centres from within schools, hospitals, mosques and civilian neighbourhoods in Gaza."
A statement from the Israeli foreign ministry said the report "serves as a propaganda tool for Hamas and other terror groups".
It noted Israel was currently carrying out investigations into “90 incidents" during the Gaza campaign.