Iran acknowledged for the first time on Monday that a rocket at its Imam Khomeini Space Center exploded after satellite photos showed the blast last week, with an official saying a technical malfunction during a test caused the explosion.
The comments by government spokesman Ali Rabiei were the first explanation offered by Iran for Thursday's explosion, which came ahead of a planned satellite launch by the Islamic Republic that the US has criticised.
Rabiei also criticised President Donald Trump for tweeting what appeared to be a surveillance photo of the aftermath of the explosion shot by a US spy satellite.
The explosion marked the third failure involving a rocket at the Iranian center, which has raised suspicions of sabotage in Iran's space programme.
However, Rabiei dismissed that, saying that "this has been a technical matter and a technical error. Our experts unanimously say so."
The image showed damaged vehicles around the launch pad, as well as damage done to the rocket's launcher. It also clearly showed a large phrase written in Farsi on the pad: "National Product, National Power."
"We don't understand why the U.S president tweets and posts satellite pictures with excitement. This is not understandable," he said. "Maybe this is because lack of Iran-related subjects that they raise such issues."