Ali Khamenei, Supreme Leader of Iran. PHOTO: REUTERS
Khamenei was speaking a day after US Secretary of State John Kerry, during a visit to Israel and the Palestinian territories, described the spate of attacks as "terrorism" that should be condemned.
Israel and the United States have long accused Iran of supplying arms to the Palestinian group Hamas, considered by Washington as a terrorist organisation.
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Tehran says it gives only moral, financial and humanitarian support.
"Despite all the efforts of the Arrogance (the United States) ... and even with cooperation from Arab countries, the Palestinian intifada (uprising) has started in the West Bank," state television quoted Ayatollah Ali Khamenei as saying.
"We will defend the movement of the Palestinian people with all of our existence, and in any way and as long as we can," Khamenei reportedly told a gathering of the Basij, Iran's volunteer militia.
Khamenei criticised those who call Palestinians "terrorists" saying they were people protesting the occupation of their land.
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Since Oct. 1, at least 86 Palestinians have been killed, some while carrying out assaults and others in clashes with Israeli forces.
At least 19 Israelis and an American have been killed in Palestinian attacks.
The bloodshed has been fuelled by Muslim agitation over increased Jewish visits to East Jerusalem's al-Aqsa mosque compound - Islam's third holiest place which is also revered by Jews as the site of two biblical-era temples.
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The Palestinians are also frustrated by the failure of decades of peace talks to deliver them an independent state.
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