Iran's Supreme Leader Ayatollah Ali Khamenei said on Thursday the United States was "deeply hated" in the Middle East and that Israel is a "cancerous tumor in the heart" of the Muslim world.
Khamenei, speaking on the same day President Obama was due to give a major speech to the Islamic world in Cairo, said the hatred felt toward America could not be changed with "slogans," according to a Reuters report.
"The nations of this part of the world ... deeply hate America," the news agency quoted Khamenei as saying.
"Even if they give sweet and beautiful (speeches) to the Muslim nation ... that will not create change," he said in a televised speech. "Action is needed."
Khamenei said the Muslim world is instead looking for practical changes to U.S. policies.
The leader's speech in Tehran marked the 20th anniversary of the death of his predecessor, Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic.
Obama is to deliver a speech in Cairo Thursday aimed at establishing a new relationship with the world's 1.5 billion Muslims after years of tense relations under the previous U.S. administration.
Iran and the U.S have had no diplomatic ties since militant students in 1979 took over the U.S embassy in Tehran.
The Associated Press contributed to this report.