One rumor said he won't run because of exhaustion; another blamed the situation on the president's workload.
The reports came after Ahmadinejad, 52, canceled a series of public appearances, including two speeches and a Cabinet meeting, The Jerusalem Post reported. A top aide to Ahmadinejad told journalists the president was "indisposed."
Iranian news Web site Shahab said doctors had advised the president to reduce his workload if he wanted to avoid illness, quoting "sources close to the government." The Web site indicated that the president had pulled out of the engagements due to fatigue caused by low blood pressure.
However, other sources in Tehran speculated that the opposition was spreading rumors about Ahmadinejad's health to garner support for next year's elections.
The Iranian presidential elections are expected to take place next June 12. So far, only one candidate has joined the race -- 71-year-old Mehdi Karroubi of the reformist movement.