U.S. ambassador to Israel Daniel Shapiro accused Israel on Monday of having separate standards of justice for Jews and Palestinians.
Shapiro said at a security conference in Tel Aviv that what he called too much Jewish vigilantism goes unchecked by Israel.
"Too many attacks on Palestinians lack a vigorous investigation or response by Israeli authorities," he said.
Prime Minister Benjamin Netanyahu called Shapiro's comments untrue and unacceptable, coming on the day of a funeral for a Jewish mother of six stabbed to death in her settlement home by a Palestinian intruder. The intruder is still at large.
Also Monday, a Jewish security guard shot another Palestinian who stabbed a pregnant woman in a West Bank settlement. She is expected to recover, and the fetus was unharmed.
Shapiro also said Monday that the U.S. is "concerned and perplexed" by continued Israeli settlement activity in the West Bank — parts of which the Palestinians want for a future state.
Shapiro said it brings into question Israel's stated commitment to eventual Palestinian independence.
Netanyahu again blamed what he said is the Palestinian leadership's incitement to violence and its refusal to recognize a Jewish state for the collapse of diplomacy.
The West Bank stabbings are part of a four-month wave of Israeli-Palestinian violence sparked by rumors that Israel was planning to take over an east Jerusalem holy site revered by Muslims and Jews.
Twenty-three Israelis and at least 136 Palestinians have been killed since September.