Israel has heavily bombarded the Gaza Strip where at least 6,500 Palestinians have been killed so far, mostly women and children, according to Palestinian health ministry figures.

This includes more than 2,700 children, more than 1,500 women, 346 elderly, and more than 17,400 wounded.

The conflict erupted after an October 7 Hamas attack on Israel killed more than 1,400 people, according to Israeli officials.

"America is a definite accomplice of criminals," said Khamenei during a speech in Tehran.

"The United States is in some way directing the crime that is being committed in Gaza."

Khamenei said the hands of Americans "were tainted with the blood of the oppressed, children, patients, women and others".

The United States, the sworn enemy of Iran, has moved two aircraft carriers into the eastern Mediterranean in a move it says is to deter Iran and Lebanon's Hezbollah, both allies of Hamas, from getting involved in the conflict.

It has also confirmed this week that it has sent a "few" military advisers to Israel as part of its support for its close ally.

Iran, which financially and militarily backs Hamas, hailed the October 7 attacks on Israel as a "success" but maintains it was not involved in the assault.

"Let everyone know that in this matter and future matters, the Palestinian nation is victorious and the future world is the world of Palestine, not the world of the Zionist regime," Khamenei said, referring to Israel.

On Tuesday, Secretary of State Antony Blinken warned Iran that the United States would respond "decisively" to any attack by Tehran proxies, as tensions rise over the conflict.

"The United States does not seek conflict with Iran. We do not want this war to widen," Blinken told a UN Security Council session.

"But if Iran or its proxies attack US personnel anywhere, make no mistake. We will defend our people, we will defend our security -- swiftly and decisively," he said.

The Islamic Republic lashed out at Blinken for what it said was his attempt to "wrongly place the blame on Iran".

"Iran categorically rejects these groundless allegations," Iran's permanent representative to the United Nations Amir Saeid Iravani said.

*This story was edited by Ahram Online