"I can tell you we are prepared to do a lot more. We will do what is necessary to defend our people and to defend our state," Netanyahu told the US pro-Israel lobby AIPAC by video link from the Jewish state's defense headquarters.
Netanyahu cut short his visit to Washington to handle the response after a rare rocket strike landed near Tel Aviv, injuring seven Israelis, just two weeks ahead of elections.
Israel hit back with airstrikes including on the office of Hamas leader Ismail Haniya, with an Egyptian-brokered ceasefire failing to take hold.
Monday's rocket comes just days ahead of the first anniversary on March 30 of Palestinian protests and clashes along the Gaza Strip's border with Israel.
An informal truce between Hamas and Israel had led to relative calm along the border, but recent weeks have seen another uptick in violence.
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