TEHRAN (CNN) -- Iranian centrist candidate Hassan Rouhani won the Islamic republic's presidential election Saturday after campaigning on a "hope and prudence" platform in which he appealed to traditional conservatives and reform-minded voters alike.
Rouhani spoke of reforms without threatening Iran's supreme leader or its institutions of which he is product. The former national security council chief promised an environment with greater personal freedoms and even indicated he would free political prisoners and jailed journalists.
In his stumping, he also pledged to improve the economy and unemployment, and as a former nuclear negotiator, he said he would reduce the high tension between Iran and the outside world by addressing sanctions related to Iran's nuclear program.
On Saturday, Iranians were dancing in the streets after his victory. Rouhani, 65, thanked voters for a high turnout, Iran's Press TV said.
In a sign of how the West is interested in how much change Rouhani could bring to Iran, the British Foreign Office immediately called upon him to set a new course for the country.
"We call on him to use the opportunity to set Iran on a different course for the future: addressing international concerns about Iran's nuclear programme, taking forward a constructive relationship with the international community, and improving the political and human rights situation for the people of Iran," a Foreign Office spokesman said.
The administration of President Barack Obama hopes "the Iranian government will heed the will of the Iranian people and make responsible choices that create a better future for all Iranians," a White House spokesman said.
"The United States remains ready to engage the Iranian government directly in order to reach a diplomatic solution that will fully address the international community's concerns about Iran's nuclear program," the press secretary's statement added.
While the White House respected the vote, it charged that the election occurred "against the backdrop of a lack of transparency, censorship of the media, Internet, and text messages, and an intimidating security environment that limited freedom of expression and assembly."
High turnout reported
Iranian officials reported a high turnout, with nearly 73% of some 50 million registered voters -- men and women, young and old -- turning out, Interior Minister Mostafa Mohammad-Najjar announced Saturday.
The lines extended into the streets at times Friday, as voters waited to pick their choice to succeed two-term President Mahmoud Ahmadinejad in the country's 11th presidential election.
Rouhani takes Ahmadinejad's mantle as one of the country's most visible figures, at a time when it's dealing with painful economic sanctions tied to international concern about its nuclear program.
But he won't be Iran's most powerful man. That distinction belongs to Ayatollah Ali Khamenei, who has been Iran's supreme leader since 1989. He's got plenty of backing, from conservative citizens to loyalist militia groups to, most notably, the Revolutionary Guard.
Rouhani has all-round credentials in Iran's institutions that include senior cleric, former commander of Iranian air defenses and legal intellectual with three law degrees, including from a university in Scotland.
He has a reputation for shunning extreme positions and bridging differences.
While he has represented Khamenei on Iran's security council since 1989, he has avoided being perceived as a pushover and has taken exception with the supreme leader on being too rigid toward the international community, according to an Iranian scholar at Stanford University.
Rouhani has accused state-run media of censorship and publishing lies.
Ahmadinejad congratulated Rouhani.
"I have always deeply believed in the vast and endless capacities of the Iranian nation for development and greatness," Ahmadinejad said. "I believe that all peaks of glory can be conquered by believing and trusting in the Iranian nation and by respecting different interests and tastes."
The other candidates were two-term Tehran Mayor Mohammad Bagher Ghalibaf, Saeed Jalili, Mohsen Rezaei, Ali-Akbar Velayati and Mohammad Gharazi.
Velayati, Ghalibaf and Jalili, who is Iran's chief nuclear negotiator, are considered close to Khamenei and would have been unlikely to challenge his authority. Of the three, Jalili had enjoyed the most popular support going into the vote.
Results showed that Rouhani secured 18.6 million votes -- or 50.7% of the 36,704,156 votes tallied.
Second was Ghalibaf, with 6.1 million votes, and third was Jalili, with nearly 4.2 million votes.
Moments after Rouhani was declared the winner, supporters started filling the area near Tehran's Haft-e-Tir Square, waving the campaign's purple flags, a witness told CNN. Motorists honked, and pedestrians held their fingers high with the V sign.
Earlier, British Prime Minister David Cameron told CNN's Richard Quest that the international community "will have to deal with whatever the