Former President Mohammad Khatami's website quoted him as saying the "current situation (in Iran) is not desirable."
Khatami warned that if it continues, the country's "social capital and international reputation will be damaged even more."
The remarks were reported late Wednesday. Khatami told a group of supporters that Iran needs an active diplomacy to decrease "international pressures and isolation."
It was the first time he spoke about the president since announcing his candidacy for the June elections last weekend. The reformist cleric is a serious challenge to Ahmadinejad, who belongs to the conservative camp.
Khatami on his way to celebrations of Islamic Revolution anniversary (Photo: Reuters)
Addressing his decision to run for president, Khatami said, "I was in a situation in which despite my gut feeling and the options of creating big problems if I compete, I accepted the majority's opinion and officially announced my candidacy."
He added, "I believe we must now be determined and aspire to change the situation and win."
'Death to Khatami' chants
According to reports Tuesday, on his way to a rally marking the 30th anniversary of the Islamic Revolution Khatami ran into an angry mob carrying sticks and chanting, "Death to Khatami."
The former president's bodyguards were forced to evacuate him to a nearby building for fear he would get hurt. He announced he would be joining the presidential race at the beginning of the week.
People running for president in Iran must receive the approval of the Council of Guardians, a body comprised of clerics appointed by Supreme leader Ayatollah Ali Khamenei, who are in charge of ensuring that the presidential candidates are loyal to Iran's constitution and to Islam.
The reformist camp claims this is essentially "a screening tool" in the hands of Khamenei, who supports the conservative camp, in order to disqualify reformist candidates.
Khatami's term as president, between 1997 and 2005, saw an improvement in the relations between Iran and the West, which was halted after Ahmadinejad took office. Last week, Ahmadinejad's assistant said the current president was interested in running for another four-year term.