Four of those injured were said to be in a critical condition.
The incident happened when two coaches of a speeding train left the tracks at Azadvar station in Joqatai, 435 miles (700km) east of the capital, Tehran, at 10.20am local time (0650 GMT) on Saturday, the broadcast said.
It is the deadliest accident since February 2004 when runaway train cars carrying fuel and industrial chemicals derailed, setting off explosions that destroyed five villages in north-eastern Iran and killing more than 200 people.
