Trump, who in recent days had expressed his displeasure over Israeli attacks in Beirut that he said could have endangered his peace deal with Iran, said Israel has been fighting Hezbollah, the Iran-aligned Lebanese militia, for "too long".
"Too many people have been killed. You don't have to knock down an apartment house every time you're looking for somebody, because there are a lot of people in those apartment houses, and they're not all Hezbollah," Trump said at the G7 summit in France on Tuesday.
His complaint comes at a moment of rising tensions with Israeli Prime Minister Benjamin Netanyahu, who has remained a key political ally despite occasional ups and downs between the two leaders over the years.
Recently, tensions have been more prominent.
Israeli officials are quietly expressing frustration about the Iran deal, while Trump is growing impatient with Netanyahu over Israeli strikes of Beirut, which triggered Iranian attacks just when he was working to finalise the peace deal.
Trump said he has a "great relationship" with Netanyahu but in the same breath added that he should be "more responsible" with Lebanon.
"Without us, without the United States, there would be no Israel. Without me, there would be no Israel, because no other president was willing to do what I did."
The two leaders have repeatedly clashed over Israel's refusal to constrain its pursuit of Hezbollah in Lebanon, where a cessation of hostilities is a key Iranian demand. Trump and other US presidents do not often criticise Israel's military tactics.
Shortly after he made his comments, an official White House social media account that typically shares clips of his public comments posted a video of those specific remarks.
The White House did not say why the official account chose to post those Trump remarks but said the president has a strong relationship with Netanyahu and that the Israel Defense Forces were "incredible partners".
"There has been no greater friend to Israel and a fighter for peace than President Trump ... Americans and our allies around the world are already safer for the United States and Israel's bold actions to deny the Iranian regime the ability to develop a nuclear weapon," a White House official said.
Israel has faced sharp criticism from other countries, particularly during its assault on Gaza that has killed 73,000 people, most of them civilians, according to the Gaza health ministry.
Israel says it never targets non-combatants and says militant groups such as Palestinian Hamas and Hezbollah regularly use civilians as human shields.
