The human rights group, which is based in London, released a report Thursday that alleged the Israeli air force carried out bomb and missile strikes on residential areas in Gaza, the Palestinian Ma'an news agency reported.
Those strikes were "disproportionate and caused heavy civilian casualties," Amnesty International said.
The Israeli navy also carried out "indiscriminate attacks" on populated coastal sites, the group said.
Amnesty International also alleged Hamas, which has control of Gaza, and other armed Palestinian groups fired missiles and other weapons into Israel, damaging civilian structures and killing civilians.
Fawzi Barhoum, a Hamas spokesman, said in a statement the report was unfair and lacked objectivity because it equated "legitimate resistance" in defense of Palestinian civilians with deliberate Israeli actions. Barhoum did not explain how firing rockets at civilian targets within Israel protects Palestinians.
Israel has yet to comment on the report.