"In the election debates, some remarks were made that were unworthy of the Iranian nation".
He is believed to favor Rohani's main challenger, the hard-line candidate Ebrahim Raisi. In a televised speech Wednesday, May 17, 2017, Khamenei called for high turnout in Friday's presidential election, urging voters to send a message to the United States.
Rivals have been trading accusations of corruption and brutality in debates and speeches aired on live television and the campaign has been the most bad-tempered in the near 40-year history of the Islamic Republic.
At a rally in Raisi's hometown of Mashhad on Wednesday, Rouhani urged the country's powerful Revolutionary Guard and other armed forces to remain impartial in the election and keep their "distance from political games".
In an apparent reference to the 2009 demonstrations, Khamenei, a hardliner who has the ultimate say in the Islamic Republic, has previously warned he would confront anyone trying to interfere in the election.
For his part, Raisi, a long-serving member of the judiciary who was one of four judges who sentenced thousands of political prisoners to death in the 1980s, attacked Rouhani for failing to deliver promised improvements to the economy.
Rouhani came to power four years ago with more than three times as many votes as his nearest rival, on promises to reduce Iran's global isolation and grant more freedoms at home.
According to Isna news agnecy Rouhani's supporters include Oscar winning film director Asghar Farhadi, who told Iranian news agency Isna "I will vote for Dr Rouhani and I hope that those who remain undecided would use their basic right and vote despite all the understandable reasons and conditions that they may have, for the fate of children in our homeland and future generations".
Although power in Iran rests largely in the ayatollah, Ali Khamenei, the results of the presidential race could lead to a more conservative government and jeopardy of the 2015 nuclear arms deal that has limited Iran as a Middle Eastern power.
If no candidate wins 50 percent of the vote on Friday, a run-off will be held a week later.
Iranian elections are overseen by a clerical body that vets candidates and bars anyone seen as posing a challenge to Iran's unique brand of theocratic rule.
Tehran residents said police deployments appeared to have been beefed up in some areas of the capital, a normal practice ahead of national polls in Iran, to prevent unrest.