The Gaza Health Ministry said a child was killed and 30 people, mostly women and children, were wounded in the strike on Monday on a house in Shati refugee camp.
An Israeli military spokeswoman told Reuters she was checking the report.
Israel earlier declared that it was holding fire in parts of the Gaza Strip for seven hours, amid world outrage over a deadly strike on a UN school in the Palestinian territory.
Monday's limited and unilateral truce, between 0700-1400 GMT, was announced after world powers fiercely condemned the previous day's attack that left 10 Palestinians sheltering at a school dead, as Israel was pulling some of its troops from Gaza.