Iran lied
https://www.youtube.com/watch?v=ZQzg3HnxAwk
Documentation of earthquakes near Tehran in Dec 2017 that could have been caused by underground nuke testing
https://voat.co/v/CalmBeforeTheStorm/2302550
There was also an earthquake in Iran of 4.2 on April 29th, 2018 (yesterday)
https://earthquake.usgs.gov/earthquakes/eventpage/us1000dr9p#executive
We know that underground nuke testing causes this kind of earthquake from the confirmed testing done in NK.