Ayatollah Nasser Makarem Shirazi in these letters stressed the responsibility of Muslim scholars to take steps to prevent such tragedies from happening again.
More than 4,700 pilgrims, including over 460 Iranians, were killed in the crush of people in Mina on September 24 when performing religious rites.
The incident marked the worst Hajj disaster ever.
Ayatollah Makarem Shirazi expressed regret over the fact that little reaction was shown to the tragedy by Muslim world scholars.
He said the life of even one Muslim is respected in Islam, so the death of hundreds of Muslims during Hajj requires efforts to find the causes of the tragedy and preventing it from happening again.
The senior cleric also suggested holding scholarly and jurisprudential meetings among Muslim scholars to discuss the issue.