Iran's official IRNA news agency says Khatami and parliament speaker Mehdi Karrubi have sent a joint letter to the country's supreme leader, Ayatollah Ali Khamenei, to complain about the conservative Guardians Council's continuing disqualification of the candidates.
As a result, say Khatami and Karrubi in their letter, Iran's voters will have little motivation to come to the polls and will not have a chance to participate in a fair ballot.
But Khatami and Karrubi stopped short of calling for a postponement of the 20 February poll.
Iran's largest reformist party, headed by Khatami's brother, Mohammad Reza Khatami, has said it will boycott the election.
As a result, say Khatami and Karrubi in their letter, Iran's voters will have little motivation to come to the polls and will not have a chance to participate in a fair ballot.
But Khatami and Karrubi stopped short of calling for a postponement of the 20 February poll.
Iran's largest reformist party, headed by Khatami's brother, Mohammad Reza Khatami, has said it will boycott the election.