Iran's new hardline President, Mahmoud Ahmadinejad, has said his surprise poll win is a blow to the country's enemies.
His comments appear to be directed at the US, which had criticised the presidential election as flawed.
In his first public statement since his victory, Mr Ahmadinejad said he wanted to "build up an exemplary, developed and powerful Islamic society".
The mayor of Tehran won 62% of the vote, nearly twice that of his rival, ex-President Akbar Hashemi Rafsanjani.
Some 22 million people voted in Friday's run-off poll - a turnout of 60%, down from 63% in the first round a week ago.
The BBC's Frances Harrison in Tehran says conservatives are now in control of every elected and unelected institution of government in Iran.
She adds that Iranians are aware that major changes are afoot, but are unsure about how far Mr Ahmadinejad will go.
In the past, when asked about social reforms, Mr Ahmadinejad has responded by saying that freedom comes from God, and that Iranians already have freedom beyond what could be imagined.
In comments carried on state radio, Mr Ahmadinejad said that although Iran had faced "the heaviest psychological war of its enemies", it had "checkmated everyone with its wide participation on Friday, and ruined all the world's calculations".
He urged Iranians to forget the rivalries of the campaign.
"Today, all competition should turn into friendship," he said. "We are part of a big family that should go hand in hand to build our proud Iran."
On the economy, Mr Ahmadinejad said he would favour Iranian companies when awarding oil contracts, and talked of removing what he called ambiguities and a lack of transparency.
Our correspondent says it is not yet clear whether this is just more of the populist rhetoric which brought Mr Ahmadinejad to power, or an indication that he is planning a major economic shake-up in the world's second largest oil producer.
Iran's supreme leader, Ayatollah Ali Khamenei, described Mr Ahmadinejad's victory as a "profound humiliation" for the US.
The White House responded to the poll result by expressing support for "those who call for greater freedom for the Iranian people".
UK Foreign Secretary Jack Straw said there were "serious deficiencies" in the election, noting that many reformists, and all women candidates, had been barred from standing.
He urged the new president to deal with international concerns over Iran's nuclear programme.
The European Union said it was ready to work with "any Iranian government" willing to progress on the questions of human rights, nuclear energy and other matters of concern.
Mr Ahmadinejad, 49, who campaigned on a conservative Islamic platform, had surprised observers by beating five other candidates in the first round to reach the run-off.
His defeated rival Mr Rafsanjani, 70, was president from 1989-97. He was the favourite going into the election and had re-cast himself as a liberal who was more willing to engage with the West.
Supporters of Mr Rafsanjani had said that victory for Mr Ahmadinejad would signal that voting fraud had occurred.
Reformist candidates accused Iran's Revolutionary Guards and Basij security services of orchestrating a plot to boost Mr Ahmadinejad.
Interior ministry officials monitoring polling stations received some 300 complaints of electoral violations in Tehran alone, the Associated Press news agency reports.
The Guardian Council, which ran the poll, has dismissed allegations of election fraud.
Mr Ahmadinejad will be Iran's first non-cleric president for 24 years when he takes office in August.