Iranian President Mahmoud Ahmadinejad cannot seek another term due to term limits.
Rafsanjani, who served two consecutive presidential terms beginning in 1989, said he was "no longer ready for this job (of president)," the semiofficial Mehr News Agency reports.
Rafsanjani was criticized by the conservative leadership for backing opposition leader and former Prime Minister Mir Hossein Mousavi during the 2009 contest.
Faezeh Hashemi and Mehdi Hashemi Rafsanjani, the daughter and son of the former president, were arrested recently for making propaganda against the state.
He was quoted by Mehr as saying he preferred a "young and energetic" person to lead to country, adding he was "forced" to run against Ahmadinejad in the 2005 election.
Iranian presidential elections are scheduled for June. Ahmadinejad's controversial re-election in 2009 sparked nationwide outrage.