Mokhtari seized the silver after throwing 8.48 meters at the Olympic Stadium in Tokyo.
Azerbaijan’s Elvin Astanov won the gold medal with a throw of 8.77 meters.
He also set a new Paralympics record in the discipline.
The bronze medal went to Ales Kisy from Czech Republic with 8.25 meters.
Powerlifters Rouhollah Rostami and Amir Jafari have won a gold a silver medal, respectively, and Amanollah Papi took a silver in javelin for Iran.