By Dan Williams
JERUSALEM (Reuters) - Israel said on Monday it was closing the Gaza Strip's main commercial crossing and limiting the Palestinian coastal enclave's fishing zone in a crackdown targeting Hamas Islamists whom it blames for border protests now in their fourth month.
"We will crack down immediately on the Hamas regime in the Gaza Strip. In a significant move, we will today shut down the Kerem Shalom (border) crossing," Prime Minister Benjamin Netanyahu said in broadcast remarks to his parliament faction.
An Israeli military statement said Kerem Shalom would remain open for the transfer of specially approved humanitarian goods. It also said Gaza's fishing zone would revert to 11 km (6 miles) after it was temporarily expanded to 17 km (9 miles).
The military statement, and separate remarks by Israeli Defence Minister Avigdor Lieberman, linked the new measures to fires from incendiary kites and helium balloons that have been flown over the border since the protests began on March 30.
The Israeli army has killed 136 Palestinians during the confrontations. Facing international censure, Israel says its lethal force has been needed to prevent armed infiltrations.
Hamas officials could not immediately be reached for comment about Monday's announcement by Israel.
Organisers say the demonstrations are expressions of popular frustration that aim to press demands such as for Palestinians' right to lands lost to Israel in the 1948 war of its foundation and for an Israeli-Egyptian blockade on Gaza to ease.
There have been no serious Israeli casualties in the Gaza border confrontations. Israel says it has lost 7,000 acres of forests and farmland to the kite- or balloon-set fires.
"We do not intend to continue absorbing and continuing with this situation," Lieberman said in separate comments to his own parliamentary faction.
Israel, which last fought a Gaza war with Hamas in 2014, does not seek a new military flare-up, he said, "but the way Hamas is conducting itself - it is simply liable to spiral out of control, and it is liable to pay the whole price, a much, much heavier price than in Operation Protective Edge (2014 war)".
Israel briefly shut Kerem Shalom in May after dozens of Palestinian torched some of the terminal's facilities on the Gaza side of the border.
On July 5, a U.S. special envoy to the Middle East, Jason Greenblatt, tweeted a picture of repair work at Kerem Shalom and accused Hamas in the "deplorable attack" on the terminal.
The administration of U.S. President Donald Trump has been watching Gaza closely as it seeks to improve humanitarian conditions while sidelining Hamas, which is blacklisted as a terrorist group in the West.
(Writing by Dan Williams; Editing by Janet Lawrence)