Thousands of people waving Iranian flags and pictures of the country's supreme leader massed Tuesday at a rally organized by the clerical regime in an apparent attempt to reclaim the streets hours after saying it would recount some disputed presidential ballots.

Later, a "massive" crowd supporting reformist challenger Mir Hossein Mousavi gathered in Vanak Square to the north, according to a correspondent for state-controlled English-language Press TV.

The government barred foreign media from covering rallies in Tehran — even the state-organized demonstration, where government officials urged the crowd not to let the election divide the nation and said the unrest would not threaten Iran's Islamic system.

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The Press TV correspondent at the pro-reform rally told the anchor by telephone that a crowd she called "huge" and "massive" was carrying banners of Mousavi, wearing green headbands and covering their mouths in an apparent defense against tear gas. She said the crowd was marching farther north, toward Tajrish Square.

The report could not be independently confirmed due to the media restrictions barring reporters for foreign organizations from reporting outside their offices.

Meanwhile, Iranian Supreme Leader Ayatollah Ali Khamenei called for a meeting with the envoys of four presidential candidates, state TV reported, as the government proceeds with an investigation into the election to calm unrest.

Khamenei urged Iranians to unite behind the cleric-led ruling system despite the demonstrations and street clashes, saying that, "In the elections, voters had different tendencies, but they equally believe in the ruling system and support the Islamic Republic."

Khamenei, Iran's ultimate authority, says that representatives of all four candidates should be present for any limited recount of disputed ballots, which the country's cleric-led Guardian Council said Tuesday that it would be willing to conduct.

The clerical government appeared to be trying to defuse popular anger and quash unrest by announcing the limited recount even as it cracks down on foreign media and shows its strength by calling supporters to the streets.

"This nation will protect and defend its revolution in any way," Gholam Ali Haddad Adel, a prominent lawmaker and supporter of President Mahmoud Ahmadinejad, said as the crowd in Vali Asr Square pumped their fists in the air and cheered in support, images on state-run television showed.

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Iranian state media said the government organized the rally to demand punishment for those who protested violently after a larger demonstration Monday by hundreds of thousands of Mousavi supporters. Mousavi has said he won Friday's balloting and has demanded the government annul Ahmadinejad's victory and conduct a new election.

In Washington, President Obama said the disputed election revealed a change in expectations among voters and perhaps their leaders, but he stopped short of saying the balloting was rigged.

"I do believe that something has happened in Iran," with Iranians more willing to question the government's "antagonistic postures" toward the world, Obama said. "There are people who want to see greater openness, greater debate, greater democracy."

Iran's state radio said seven people were killed in clashes from Monday's protest — the first official confirmation of deaths linked to the street battles following the disputed election.

Witnesses saw people firing from the roof of a building used by a state-backed militia after some Mousavi supporters set fire to the building and tried to storm it.

Mousavi supporters had called for demonstrations Tuesday but Mousavi said in a message in his Web site he would not be attending any rally and asked his supporters to "not fall in the trap of street riots" and "exercise self-restraint."

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Ahmadinejad traveled to Russia Tuesday after delaying a trip for a day but did not mention the Iranian election or unrest. Instead, he focused on the traditional target of the Islamic Republic's ire, the United States.

"America is enveloped in economic and political crises, and there is no hope for their resolution," he said through an interpreter. "Allies of the United States are not capable of easing these crises."

An Iranian state radio announcement that seven people were killed in Monday's protests was the first confirmation of deaths linked to the three days of violent demonstrations that started Saturday after the election results were announced. It said people were killed during an "unauthorized gathering" at a mass rally after protesters "tried to attack a military location."

"Those who voted for Mr. Mousavi. Those who are creating unrest. Those who break glass, smash windows, and vandalize. Those who threaten people. It is not the right thing to defend these people," said Adel, a former parliament speaker.

Foreign reporters in Iran to cover last week's elections began leaving the country Tuesday after Iranian officials said they would not extend their visas.

Authorities restricted other journalists, including Iranians working for foreign media from reporting on the streets, and said they could only work from their offices, conducting telephone interviews and monitoring official sources such as state TV.

At least 10 Iranian journalists have been arrested since the election, "and we are very worried about them, we don't know where they have been detained," Jean-Francois Julliard, secretary general of Reporters Without Borders told AP Television News in Paris. He added that some people who took pictures with cell phones also were arrested.

The rules prevent media outlets, including The Associated Press, from sending independent photos or video of street protests or rallies.

Khamenei ordered the Guardian Council, an unelected body composed of 12 clerics and experts in Islamic law closely allied to the supreme leader, to investigate the election results after he met with Mousavi on Sunday. Mousavi also sent a letter to the supreme leader outlining his allegations.

A spokesman for the Guardian Council, Abbas Ali Kadkhodaei, was quoted on state TV as saying the recount would be limited to voting sites where candidates claim irregularities took place. He did not rule out the possibility of canceling the results, saying that is within the council's powers, although nullifying an election would be an unprecedented step.

Mousavi said Monday he was not hopeful that the council would address his charges because he believes its members are not neutral and have already indicated support for Ahmadinejad.

Unlike past student-led demonstrations against the Islamic establishment, Mousavi has the ability to press his case with the highest levels and could gain powerful allies. Some influential clerics have expressed concern about possible election irregularities and a fierce critic of Khamenei, former President Hashemi Rafsanjani, is part of the ruling establishment.