Recently he demanded that the authorities change their uncompromising position toward former presidential candidates Mir Hussein Musavi and Mehdi Karrubi who have been under house arrest for almost three years. Harsh reactions by hard-liners followed.
But on January 12, Motahari released the text of a letter he sent to Mohammad Javad Larijani, who heads the clerically dominated judiciary's human rights committee.
In the letter, Motahari accuses the official of feigning ignorance regarding the 2009 postelection protests and telling him that he has "caught a political common cold."
The rebuke apparently came in response to comments Larijani made earlier, in which he said the protest movement was basically stopped three years ago, alluding to the house arrest of the opposition candidates.
Iranian hard-liners describe the huge demonstrations in 2009 as sedition and even a coup attempt against the regime, while various opposition forces and many Iranians believe it was the result of genuine popular anger that stemmed from the contentious presidential election result.
While Musavi appeared to be running strong prior to the vote, Ahmadinejad's victory by a wide margin was declared almost immediately after the polls closed. Within hours, thousands of people poured onto the streets claiming fraud and the demonstrations continued and got larger.
They were the most threatening and dangerous antiregime protests since the establishment of the Islamic republic in 1979. In 2011, the authorities put Musavi and Karrubi, who had by then become the de facto leaders of the opposition, under house arrest.
"You also feel that people have not accepted all the one-sided things you have told them in these last four years," Motahari writes in his letter to the hard-line official. The people, he goes on to say, are not sure about the fate of the 2009 protests, just as they are not sure about the fate of Larijani's farming and grazing lands.
Motahari was alluding to a scandal involving Larijani, whose two brothers head the judiciary and the parliament, respectively. Last summer, Tehran's prosecutor launched a case involving large tracts of national land near Varamin, which Larijani has allegedly taken over and is using as grazing land for herds of sheep and camels.
"We, ourselves turned the civic protests into sedition by our own mismanagement and by not grasping the language of civic protest," Motahari goes on to write. Then, in order to somehow contain it, we presented it as a full-blown coup d'etat against the regime and followed up by using every tool to prove our claim."
Motahari's barrage of criticism comes at a time when the hard-liners are trying to beat back against any hint of domestic change and political relaxation. As nuclear negotiations with the West show signs of success, they appear nervous about holding the line domestically by taking an uncompromising stance with regard to the two jailed presidential candidates, culture, media freedoms, and Internet censorship.
Ali Motahari is the son of Ayatollah Morteza Motahari, one of the ideologues and leaders of the Islamic Revolution, who was a close disciple of the leader of that revolt, Ayatollah Ruhollah Khomeini.
-- Written by Mardo Soghom based on reporting by RFE/RL's Radio Farda