Editor's note: Read this report in Arabic
(CNN) -- Iran and the United States rang in the Persian new year Tuesday with distinctly different messages for the Iranian people.
President Barack Obama slammed the Islamic Republic's crackdown on electronic communications and Ayatollah Ali Khamenei warned that Iran would not hesitate to strike back in the event of an attack on the Islamic republic.
The beginning of the year 1391 took Khamenei to the massive Imam Reza shrine complex in the eastern city of Mashhad, where thousands jammed the mosque to hear the nation's supreme leader.
Khamenei denied Iran has nuclear capability or that it is trying to develop atomic weapons. But he warned that Iran will defend itself if the United States or Israel attacks -- words that only increase anxiety in Iran's nuclear showdown with world powers.
Sporadic chants of "Death to America" erupted during Khamenei's pauses in between his declarations of Iran's greatness and the West's inability to tear down the Islamic revolution's achievements.
Khamenei said the main reason for the West's enmity toward Iran has to do with its desire to control Iran's vast oil reserves.
"A nation's prowess all depends on energy, on oil," he said. "It's the Islamic Republic of Iran that they have a problem with because this republic has stood like a lion in their face."
Khamenei also urged Iranians to support domestic production to stave off the debilitating effects of international sanctions. He said the government must cooperate with local industries and financial institutions to boost production.
He urged Iranians to buy local -- saying that Iranian-made products are just as good as foreign brands.
"You must seek Iran-made products," he said. "It's in your hands, the hands of the people. When you consume, consume indigenously."
Obama, on the other hand, used the holiday, known as Nowruz, to remind the world of the Tehran regime's attempts to curb the flow of information in and out of Iran.
"Like the iron curtain of the 20th century, an electronic curtain is descending as the Iranian regime attempts to control what its citizens see and hear,' Obama said in a video new year's message posted on YouTube in English, with Farsi and Arabic subtitles.
"To the people of Iran, this holiday comes at a time of continued tension between our two countries," he said.
"But as people gather with their families, do good deeds, and welcome a new season, we are also reminded of the common humanity that we share. There is no reason for the United States and Iran to be divided from one another.
"Yet increasingly, the Iranian people are denied the basic freedom to access the information that they want. The Iranian government jams satellite signals to shut down television and radio broadcasts. It censors the Internet to control what the Iranian people can see and say. The regime monitors computers and cell phones for the sole purpose of protecting its own power. And in recent weeks, Internet restrictions have become so severe that Iranians cannot communicate freely with their loved ones."
As a result of "the actions of the Iranian regime," Obama said, "an electronic curtain has fallen around Iran -- a barrier that stops the free flow of information and ideas into the country, and denies the rest of the world the benefit of interacting with the Iranian people, who have so much to offer."
The Nowruz messages come at a time of heightened tensions between Iran and world powers.
The United States and the European Union have targeted Iranian banks in an effort to persuade Iran to abandon any nuclear weapon ambitions. A nuclear watchdog agency report in November said Iran could potentially be developing a bomb.
Israel has even hinted at pre-emptive strikes on Iranian nuclear plants to set shut down or, at least, set back Iran's program. Obama and Israeli Prime Minister Benjamin Netanyahu recently discussed the matter at the White House.
Iran has been reeling under the crush of sanctions that have severely devalued the currency and spiked prices of food and other basic commodities.
Some Iranians told CNN that their Nowruz celebrations would be sharply tempered this year because of the economic situation -- they simply could not afford it.
Khamenei urged unity among Iranians at this time. Disunity, he said, only emboldens Iran's enemies.
"I hope 1391, which begins today, will be joyful for our nation,' Khamenei said. "God almighty, defeat the enemies of this great nation."