The ceasefire was brokered by Egyptian mediators, and encompassed not only Hamas but also other Palestinian militant groups in the enclave. The truce expired at 04:00 GMT.
"We announce that the calm between us and the Zionist enemy has finished entirely, and it will not be renewed as a result of the occupation's denial of its fundamental conditions and obligations," Hamas's armed wing, Izz el-Deen al-Qassam, announced.
Hamas says that Israel failed to lift the blockade of the Gaza Strip, which it says was a condition of the ceasefire. Israel denies this.
On Thursday, Palestinian militants fired a combination of rockets and shells towards southern Israel, while Israeli planes fired rockets into the Gaza Strip, killing one person and injuring three others.
Israel had insisted the truce was indefinite and defense officials said on Thursday the airstrikes were a warning to Hamas.
Hamas seized control of the Gaza Strip in June 2007.
Shortly before Hamas' expected announcement, Israeli Defence Minister Ehud Barak told Israel's Haaretz newspaper that the truce had been beneficial, saying it was "not a mistake."
"If the quiet continues, there will be quiet. If the calm breaks, we will operate," he said.
