Pro-Ahmadinejad newspapers announced the Guardian Council's approval in large type on their front pages. Newspapers backing his main reformist challenger, Mir Hossein Mousavi, mentioned the news in small references.
Mousavi has said Ahmadinejad stole re-election through fraud and demanded a new election. Western analysts have described Ahmadinejad's roughly 2-1 margin of victory as suspicious and improbable.
The decision ruling out the possibility of a new vote was expected after the country's supreme leader endorsed the vote on June 19. The government had delayed a formal declaration as Mousavi supporters flooded in the streets in protests that were put down through a show of force by riot police and pro-government militiamen.
Ahmad Mirzai, a 45-year-old worker at a private Tehran company, said the council's decision "was fair and based on reality. Iranians love Ahmadinejad and if he runs for another election, again, the result will be the same."
But a 35-year-old high-school teacher, Sahar, said she knew the council would approve the result.
"I am not convinced, she said. "Everybody who I knew voted for Mousavi. The council was not a fair judge."
In a sign that a political purge may be afoot in Iran's most important economic sector, the independent news agency Fararu reported that three senior officials from the oil ministry were leaving their jobs.
All three were prominent members of former president Mohammad Khatami's government, and considered allies of former president Ali Akbar Hashemi Rafsanjani. Both former presidents were considered to be backers of Mousavi's bid for the presidency
The Guardian Council, an electoral authority the opposition accuses of favoring Ahmadinejad, said Monday that it had found only "slight irregularities" after randomly selecting and recounting 10 percent of nearly 40 million ballots.
"From today on, the file on the presidential election has been closed," Guardian Council spokesman Abbas Ali Kadkhodaei said on state-run Press TV.
Conservative Ayatollah Ahmed Jannati, who heads the Guardian Council, said that "meticulous and comprehensive examination" revealed only "slight irregularities that are common to any election and needless of attention," according to the state TV channel IRIB.
Mousavi has made few public appearances since then and said he would seek official approval for rallies.
The cleric-led government has said Ahmadinejad will be sworn in for a second term as early as July 26.
Asked if the United States would recognize Ahmadinejad as Iran's legitimate president, U.S. Secretary of State Hillary Rodham Clinton said "We're going to take this a day at a time."
Monday's recount appeared to be an attempt to cultivate the image that Iran was seriously addressing fraud claims, while giving no ground in the clampdown on opposition.
Ahmadinejad would still have beat Mousavi if errors were found in nearly every one of the votes in the recount, according to the government.
"They have a huge credibility gap with their own people as to the election process. And I don't think that's going to disappear by any finding of a limited review of a relatively small number of ballots," Clinton told reporters in Washington.
Ahmadinejad also said he had ordered an investigation of the killing of a young woman on the fringes of a protest. Widely circulated video footage of Neda Agha Soltan bleeding to death on a Tehran street sparked outrage worldwide over authorities' harsh response to demonstrations.
Iran's leaders have been trying to blame the election unrest on foreign conspirators, a longtime staple of government rhetoric about internal dissent.
Ahmadinejad's Web site said Soltan was slain by "unknown agents and in a suspicious" way, convincing him that "enemies of the nation" were responsible.
An Iranian doctor who said he tried to save her told the BBC last week she apparently was shot by a member of the volunteer Basij militia. Protesters spotted an armed member of the militia on a motorcycle, and stopped and disarmed him, Dr. Arash Hejazi said.
Basij commander Hossein Taeb on Monday alleged that armed impostors were posing as militia members, Iran's state-run English-language satellite channel Press TV reported.