Netanyahu’s office said the 73-year-old was admitted to Sheba Hospital, close to his private residence, after experiencing dizziness, and would stay there overnight.
In a video from hospital, a smiling Netanyahu said he had taken holiday on Friday at the Sea of Galilee in temperatures hitting 38 Celsius (100.4 Fahrenheit).
“Thank God, I feel really well,” he said.
“I ask you all, spend less time in the sun, drink more water, and may we all have a good new week,” he added.
Israel’s longest-serving leader is in the middle of a domestic crisis with protests against his religious-nationalist coalition’s push for judicial reform before parliament disperses for the summer on July 30.
That furor has contributed to strains in relations with the United States, as have surging Israeli-Palestinian violence and progress in Iran’s nuclear program.
Netanyahu’s office said Sunday’s scheduled cabinet meeting would instead be held Monday.
Israeli media said he was fully conscious en route to Sheba and that he walked into the emergency room. No procedures were enacted to declare him incapacitated or determine who might replace him, the reports added.
When then-Prime Minister Ariel Sharon was felled by a stroke in 2006, he was succeeded by his deputy, Ehud Olmert. Justice Minister Yariv Levin has stood in for Netanyahu during foreign trips.
Netanyahu’s office said he was admitted on his physician’s recommendation after complaining of “light dizziness.”
“The preliminary diagnosis is dehydration,” it said, adding further routine tests were underway.
First elected to top office in 1996, Netanyahu has been both dynamic and polarizing. He spearheaded a free-market revolution in Israel while showing distrust of internationally backed peacemaking with the Palestinians and world powers’ negotiations to cap Iran’s nuclear program.
With hundreds of military reservists threatening not to heed call-up orders in protest at the government reforms, Israel’s Channel 13 on Wednesday aired audio of Netanyahu shouting in a Cabinet session that such insubordination was inconceivable.
Critics fear the judicial overhaul plan aims to curb court independence by Netanyahu, who is on trial for corruption charges that he denies. He says the reforms would balance out branches of government.
“I wish the prime minister a full recovery and good health,” tweeted Yair Lapid, the centrist leader of the opposition.
In Washington, a spokesperson for the White House National Security Council said: “We wish him a speedy recovery.”
In early October, Netanyahu was taken ill during the Jewish fast of Yom Kippur and was also briefly hospitalized.