The IDF last week destroyed an underwater tunnel created to allow Hamas access to Israel's territory through the sea, the IDF Spokesperson's Unit said Sunday.
The Israeli military has come under intense worldwide criticism for permitting its forces to open fire on unarmed protesters in Gaza.
The IDF said the tunnel would have enabled Hamas naval commandos to carry out amphibious terrorist attacks against Israel.
"We continue to monitor using all our operational, technical and intelligence capabilities that we have at our disposal".
Israel has placed a high priority on eliminating the tunnel threat since Hamas gunmen infiltrated Israel during the 2014 war.
A high-level Israeli military official, who would only speak on condition of anonymity, suggested Hamas had dozens of divers. Israel assumes there are other under sea tunnels.
There was no immediate word from Hamas, a group sworn to Israel's destruction, which rarely comments on specific strikes on its infrastructure.
The destruction of the tunnel was part of an extensive operation targeting Hamas' naval forces. He said they had diving gear that doesn't leave a trace above water. But once inside they would have been able to put on diving suits and assemble weapons.
On Friday, four Palestinians were killed and 500 injured in clashes with IDF forces along the Israel-Gaza border.
Protests peaked on May 14 when at least 61 Palestinians were killed in demonstrations to coincide with the controversial opening of the U.S. embassy in Jerusalem.