Speaking on the occasion, Ayatollah Khamenei instructed all state bodies to cooperate with the Health Ministry and provide it with all required equipment to combat the spread of coronavirus nationwide, Financial Tribune reported.
The symbolic ceremony is performed annually around March 5 with the aim of promoting the culture of respect for trees and other forms of plants.
The Leader described planting trees as a move with great blessings, but his speech mainly focused on the recent outbreak of the coronavirus disease that has so far killed tens of people in Iran and over 3,000 worldwide.
He said the dedicated efforts of the medical personnel in treating these patients indicate their sense of humanitarian responsibility and commitment.
"As I had already thanked doctors, nurses and other health staff heartily, I feel obliged to hereby thank them … once again," he said, Leader.ir reported.
Ayatollah Khamenei had earlier expressed his gratitude to health officials and personnel in a video on Thursday.
He also advised people to follow the instructions of health authorities on personal hygiene to prevent the spread of the virus.
"God has ordered us to feel responsible about our own and others' health," he said.
The Leader stressed that this crisis is not that serious, as there have been worse situations in the past and called on the public to rely on God and pray.
He described the epidemic as a passing and non-emergency situation, saying what remains after its end would be valuable experiences for the future.
"The armed forces and organizations affiliated to the Leader's office have also been tasked to do the same," he said.