TEHRAN - Thousands of people began massing in the streets here again on Tuesday to protest Iran's disputed presidential election, increasing tensions a day after clashes left at least seven people dead during the largest antigovernment demonstration since the Iranian revolution.
But in answer to the supreme leader's turnabout call for an examination of opposition charges of vote-rigging, the country's powerful Guardian Council said Tuesday it was prepared to order only a partial recount, and it ruled out an annulment of the vote, according to state television and news reports.
The concession was rejected by the main opposition candidate, Mir Hussein Moussavi, and other opponents of the declared winner, President Mahmoud Ahmadinejad. The opponents demand that a new election be held.
As the political tumult grew, the Iranian government canceled all foreign press credentials and told Iranian journalists they could report only from their offices, but news continued to flow out of Tehran.
Meanwhile, Mr. Ahmadinejad appeared to try to project a secure grip on power, leaving Iran to fly to Russia on Tuesday for a meeting on international security.
Seeking to reclaim the initiative after the opposition's enormous show of strength on Monday, Mr. Ahmadinejad's supporters called for a their own rally on Tuesday, and demonstrators from both camps began to gather in the same part of Tehran.
A spokesman for Mr. Moussavi was quoted as urging them not to attend "to protect their lives," Reuters reported.
In Twitter feeds and on Web sites - a primary source of communication for the opposition - Mr. Moussavi's supporters asked that protesters wear black in honor of the seven killed Monday.
Speaking at Monday's huge rally, Mr. Moussavi said he had written to the Guardian Council to complain about the election but had little hope of action from the panel because many of its members had supported Mr. Ahmadinejad ahead of the election.
"I believe annulling the election results would be the least harmful measure," he said. "Otherwise people will no longer have confidence in the system and the government," he said. But the Guardian Council rejected that demand, Reuters reported.
"Based on the law, the demand of those candidates for the cancellation of the vote, this cannot be considered," the spokesman, Abbas Ali Kadkhodaei, a spokesman for the Guardian Council, told state television, Reuters said.
Mr. Ahmadinejad flew to Yekaterinburg, Russia, for a summit meeting of the Shanghai Cooperation Organization, grouping Russia, China and four central Asian states. At the gathering, Mr. Ahmadinejad did not mention the Iranian election, but gave a speech in which he referred to regional problems, describing Iraq, Afghanistan and Palestine as occupied and unstable.
"The world is gripped by economic and political crises, and there is no hope for their solution," he said. "The countries allied with America are also in no condition to cope with these crises."
He added: "The current political and economic order is approaching the end of its mastery of the world. It is absolutely clear that the epoch of empire has come to an end."
Mr. Medvedev did not offer any public comments on the Iranian election. He later met on the sidelines of the conference with Mr. Ahmadinejad, Kremlin officials said.
In contrast with doubts expressed in many west European capitals over the validity of the Iranian ballot, a deputy foreign minister of Russia, Sergei Ryabkov, told reporters that Russia had warm relations with Iran.
"Elections in Iran are an internal affair of the Iranian people, but we welcome the newly elected president of that state," Mr. Ryabkov said.
On Monday, hundreds of thousands of people from across Iranian society poured into the streets to protest what they charge were fraudulent results in last week's vote. The protests initially were believed to have been largely peaceful and only one death was reported.
But violence erupted after dark when protesters surrounded and attempted to set fire to the headquarters of the Basij volunteer militia, which is associated with the Revolutionary Guards, according to news agency reports.
State radio said seven people died after an "unauthorized gathering" following Monday's mass rally when protesters tried to attack "a military location," the A.P. said.
Ayatollah Khamenei, Iran's supreme leader, was compelled to respond to the popular and sustained defiance and called Monday for a formal review of the results, the first hint that the government might fear it could not control the crowds. But Mr. Ahmadinejad's decision to leave the country as head of state threatened to inflame voters. Mr. Ahmadinejad had already incensed protesters when he compared them to angry soccer fans whose team had lost and called them "dust."
One demonstrator fired off a Twitter message, one of thousands of brief electronic dispatches that kept the outside world up-to-the-minute on the protests, proclaiming: "Ahmadinejad called us dust, we showed him a sandstorm."
The silent march through central Tehran on Monday represented an extraordinary show of defiance from a broad cross section of society and some protesters began to sense that the leadership's firm backing of Mr. Ahmadinejad had wavered.
In his first public comment on the situation in Iran, President Obama said he was deeply troubled by postelection violence and called on Iranian leaders to respect free speech and the democratic process. He told reporters he would continue pursuing a direct dialogue with Tehran, but he urged that any Iranian investigation of election irregularities be conducted without bloodshed.
The protests showed how the government's assertion that Mr. Ahmadinejad won re-election by a margin of almost two to one had further cleaved Iranian society into rival camps.
On one side are the most powerful arms of the Islamic system of government: Ayatollah Khamenei; the military; the paramilitary; and the Guardian Council. On the other is a diverse coalition that has grown emboldened by the day, with some clerics joining two former presidents and Mr. Moussavi, the former prime minister and main opposition candidate, who addressed the crowd from the roof of a car near Freedom Square in downtown Tehran.
Earlier Monday, Ayatollah Khamenei stepped in to try to calm a growing backlash, forcing him into a public role he generally seeks to avoid as the country's top religious authority. Under Iran's dual system of government, with civil and religious institutions, the supreme leader can usually operate in the shadows, while elected officials serve as the public face of Iranian governance and policy.
He called for the Guardian Council to conduct an inquiry into the opposition's claims that the election was rigged and then had that announcement repeated every 15 minutes on Iranian state radio throughout the day. It was a rare reversal.
Nazila Fathi reported from Tehran, and Alan Cowell from Paris. Bill Keller reported from Tehran, Clifford J. Levy from Moscow and Andrew E. Kramer from Yekaterinburg, Russia.