The assailant fled the scene on foot. Police and emergency services team are on the scene and a manhunt is in progress.
The man was evacuated to Hadassah Ein Kerem Hospital in Jerusalem.
According to the police, "An Arab assailant attacked a Jewish haredi man near the Nablus Gate. He struck him on the head and the two struggled shortly, before the assailant fled the scene."
The ax was found at the scene.
Magen David Adom Spokesman Zaki Heller told Ynet that, "At 8:21 am we received a call saying a man was attacked on the corner of HaNevi'im and Bar-Lev streets, near the Nablus Gate.
An ambulance arrived at the scene within minutes. The paramedics found the man who was attack sitting on the sidewalk and presenting with head and torso injuries. He told them he had fought off his assailant.
Heller added that the man suffered wounds to the back of his head, his hands and his waist, adding he told paramedics he was attacked by an Arab man.