Israeli military spokesman Peter Lerner said the tunnel he accused Hamas of building extended several hundred metres (yards) into Israel though no exit had been constructed.
He declined to provide specifics on how it was "neutralised". The operation was carried out "earlier this week," he said.
"This tunnel is the first one to be found since Operation Protective Edge," Lerner told journalists, referring to the 2014 war.
"It was built by Hamas in order to infiltrate and execute terror attacks against the people of the southern communities and (military) forces in that area."
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It was the third war in Gaza since 2008 and the longest, deadliest and most destructive.
It killed 2,251 Palestinians, while more than 10,000 were wounded and 100,000 were left homeless.
On the Israeli side, 73 people were killed, of whom 67 were soldiers. Up to 1,600 were wounded, according to the United Nations.
There have been a number of tunnel collapses within Gaza in recent months, including those extending toward Egypt. Several Gazans have been killed.