The bombing resulted in the death of 19 Iranian sailors leaving 15 others injured.
Twelve badly wounded sailors were taken to a local hospital which also treated another three with slight wounds.
The friendly fire hit The Konarak, a Hendijan-class support ship near the port of Jask, 790 miles south-east of Tehran.
Konarak had been remodeled in 2018 and was able to launch sea and anti-ship missiles.
The 47-metre vessel which has been in service since 1988, had the capacity of 40 tons and carries a crew of 20 sailors.
It was the second deadly incident involving a misfired missile by Iran in 2020.
In January, the country’s paramilitary Revolutionary Guard accidentally shot down a Ukrainian jetliner.
All 176 people on board were killed.