Iran's Supreme Leader Ayatollah Ali Khamenei urged a large turnout in presidential elections on Friday, and said he did not "give a damn" about U.S. suggestions that the ballot was unfair.
"What is important is that everyone takes part," Khamenei said, speaking live on state television as he cast his ballot in the capital Tehran.
"Our dear nation should come (to vote) with excitement and liveliness, and know that the destiny of the country is in their hands and the happiness of the country deppends on them."
Friday's vote is Iran's first presidential election since 2009, when a disputed win for Mahmoud Ahmadinejad led to months of unrest in the Islamic Republic.
Khamenei derided Western misgivings about the credibility of the vote.
"I recently heard that someone at the U.S. National Security Council said 'we do not accept this election in Iran'. We don't give a damn," he said.
On May 24 U.S. Secretary of State John Kerry called into question the credibility of the election, criticising the disqualification of candidates and accusing Tehran of disrupting Internet access.
Iran's Guardian Council, the state body that vets all candidates, has barred a number of hopefuls from the roster in the ballot, including former president Akbar Hashemi Rafsanjani, who is seen as sympathetic to reform.
Iranians can choose from a slate of six largely conservative candidates in the election, all of whom were approved to run by the Guardian Council.
Khamenei said he had told no one of his favourite for the presidency.
"Among those running ... I had someone in mind who I chose. I haven't told anyone (of my vote). Even those close to me like my family and children don't know who I voted for," he said.
Khamenei urged officials running the ballot to keep in mind that "people's votes are left in trust with them."