The Israel Air Force has struck four targets in the northern Gaza Strip despite the Egypt-brokered truce, says the Israel Defence Forces.
Areas controlled by Hamas were targeted in the strikes, which are part of an eruption of violence taking place along the Israel-Gaza border which has also seen Israelis and Palestinians exchanging fire.
There were no immediate reports of casualties in the flare-up along the frontier, which has been largely quiet since a 2014 war.
The attacks have coincided with work by the Israeli military to uncover tunnels being built by people in Gaza that Israel fears could be used to infiltrate its territory.
The Palestinian fighters fired mortar bombs at Israeli forces operating near the border fence, prompting fire from Israeli tanks and warplanes that bombed open areas in the northern and southern sectors of the Gaza Strip.
"Our efforts to destroy the Hamas terror tunnel network, a grave violation of Israel's sovereignty, will not cease or be deterred," military spokesman Lieutenant-Colonel Peter Lerner said.
The Hamas armed wing, Izz el-Deen Al-Qassam Brigades, said the raid was a violation of the 2014 ceasefire and demanded that Israel pull out its forces immediately.
"The enemy must not make pretexts and must leave Gaza immediately, they should deal with their fears and concerns outside the separation line," the group said in a statement.
A senior Hamas official in exile, Moussa Abu Marzouk, said calm along the Gaza-Israel border was being restored following intervention with the two sides on the part of Egypt, which brokered the truce that stopped the 2014 war.
"Contacts were made with Egyptian brothers, who sponsored the last ceasefire agreement. Their response was quick, serious, which helped restore things to where they were before," Abu Marzouk in a post on his official Facebook page.
Earlier this week, Israeli Prime Minister Benjamin Netanyahu inspected a large tunnel discovered in April on the Israeli side of the border. Israel said it had been dug by Hamas.
Israeli security sources say half a dozen classified anti-tunnel technologies have long been under development, though held up by funding problems that were partly alleviated by a US research grant of $40 million this year.
Hamas leaders, while stressing they do not seek an imminent war, see tunnels as a strategic weapon in any armed confrontation with Israel and have vowed not to stop building them.
The 2014 conflict caused more than 2100 Palestinian casualties -- mostly civilians -- while just 67 Israeli soldiers and six Israeli civilians were killed.
Reuters / Newshub.