Hamas had earlier said it would not be renewing the truce when it expired at 0400 GMT on Friday.
The Egyptian-brokered deal began on 19 June but has been tested regularly by Palestinian rocket attacks on Israel and Israeli operations in Gaza.
Israel said it would like to renew the truce, but Hamas said Israel failed to ease its blockade of Gaza.
Israeli officials insist they never made a commitment to do so.
Both sides have accused the other or regularly infringing the truce.
"The ceasefire is over and there won't be a renewal because the Zionist enemy has not respected its conditions," Hamas said in a statement carried on its website.
As the expiry of the ceasefire neared, both sides said they would respond to any attack from the other party but would not take the offensive.
"We issue a warning to the Zionist enemy: all attacks against the Gaza Strip or any new crime will trigger a large-scale confrontation and we will retaliate very fiercely," said the Hamas statement.
Speaking to Israel's Haaretz newspaper before the ceasefire was declared over by Hamas, Defence Minister Ehud Barak said the truce had been beneficial.
"Of course the tahadiyeh (calm) was not a mistake," he told Haaretz.
"If the quiet continues, there will be quiet. If the calm breaks, we will operate."
However, there have been regular outbreaks of violence in recent weeks with Palestinian factions firing rockets at Israel from Gaza and Israel responding with airstrikes.