After images of women without hijabs participating in a race on Friday appeared online, such a decision was made.
Two thousand women and three thousand men participated in a marathon on Kish Island near Iran's southern coast.
Some of the participants wearing red t-shirts were not wearing hijabs or other coverings.
This provoked very different reactions.
Most supporters of change in Iran welcomed the photos with satisfaction as another sign of Iranian women rejecting the restrictions on how to dress imposed by the authorities.
In turn, the Iranian government regarded this as an unacceptable protest against the existing situation.
Subsequently, judicial authorities quickly took action against the organizers.
The fact that some participants not only violated the rules of wearing hijab, but also the very fact of holding a marathon, caused condemnation from the country's theocratic Islamic leadership.
