The announcement from Iran's powerful Guardian Council -- a 12-member panel that has the authority to annul or validate the election -- was the clearest yet in ruling out a new election. Results of the poll show President Mahmoud Ahmadinejad winning re-election by a landslide with 62.6 percent of the vote.
Ahmadinejad's main challenger, Mir Hossein Mousavi, has charged massive fraud and insists he is the true winner. Another defeated candidate, pro-reform cleric Mehdi Karoubi, has also questioned the legitimacy of the vote.
The claims have fueled days of political protests in Iran and signaled widening rifts among the country's influential ruling clerics. At least 17 people have been killed in near-daily demonstrations, including at least one that drew hundreds of thousands of protesters.
During a White House press conference Tuesday, President Barack Obama said the United States and the entire world was "appalled and outraged" by Iran's violent efforts to crush the protests.
Listen to President Obama's entire press conference, where he addressed Iran, health care and other issues:
"I have made it clear that the United States respects the sovereignty of the Islamic Republic of Iran, and is not interfering in Iran's affairs," President Obama said. "But we must also bear witness to the courage and dignity of the Iranian people, and to a remarkable opening within Iranian society. And we deplore violence against innocent civilians anywhere that it takes place."
One Iran analyst said President Obama is walking a delicate line between condemning the violence against the protesters and staying out of the political fray.
"There is a long and rich political tradition within Iran of labeling one's opponents as lackeys of America, stooges of Britain," said Afshin Molavi of the New America Foundation. "The Mousavi challenge to the current order of the Islamic Republic is surprisingly in many ways indigenous, organic and homegrown, and I don't think they would benefit from Barack Obama siding with him."
Listen to Molavi's entire interview here:
On Tuesday, the Guardian Council found "no major fraud or breach in the election," a spokesman, Abbas Ali Kadkhodaei, was quoted as saying by Iran's state-run English language Press TV, according to the Associated Press. "Therefore, there is no possibility of an annulment taking place."
Iranian officials have intensified their warnings against continued protesting in recent days. Iran's Revolutionary Guard warned demonstrators Monday they would face a "revolutionary confrontation" if they continued to protest the election.
Ebrahim Raisi, a top judicial official, confirmed Tuesday that a special court has been set up to deal with detained protesters.
"Elements of riots must be dealt with to set an example. The judiciary will do that," he was quoted as saying by the state-run radio, according to the AP. The judiciary is controlled by Iran's ruling clerics.
Foreign news organizations have been largely banned from covering the protests, curbing the flow of information in and out of the country amid the unusual show of political defiance.
Tehran riot police clashed with protesters Monday, firing tear gas and live bullets to break up about 200 demonstrators paying tribute to those killed in the protests, including a young woman, Neda Agha Soltan, whose apparent shooting death was captured on video and circulated worldwide.
Trucks and police in riot gear were deployed on the main squares of Tehran on Tuesday, but media reports indicated no signs of any protest gatherings in the city by mid-afternoon.
Across the world, governments and diplomats were looking to stake positions in the Iranian showdown, which is shaping up to be the strongest challenge to the rule of Islamic clerics in 30 years.
Ahmadinejad won a critical nod of support Russia Tuesday, with the Foreign Ministry in Moscow saying it respects the declared election result. Russia has deep economic and political ties with Tehran.
Separately, in New York, U.N. Secretary Ban Ki-moon urged an "immediate stop to the arrests, threats and use of force," U.N. spokeswoman Michele Montas said Monday.
For its part, Iran has stepped up allegations of foreign interference in its internal affairs over the last few days.
Iran accused the U.N. chief Tuesday of interfering in its state affairs in his comments, the ISNA news agency reported.
"Mr. Ban Ki-moon, under the influence of some powers, is ignoring the realities of Iran's election and his remarks are clearly contradicting his duties ... and are a clear interference in Iran's state matters," it quoted Foreign Ministry spokesman Hassan Qashqavi as saying, according to Reuters.