Images of the fountains first appeared on the social media account 1500 Tasvir, which shares content related to the protests in Iran on several different social media platforms.
Reuters has identified the locations by looking at buildings and statues, but it is still unclear when the action took place.
According to the BBC's Persian news service, the fountains have now been emptied of water, but red traces can still be seen at the bottom.
On the internet, however, they live on and Twitter users hail the move as a work of art that they named "Tehran covered in blood".
During Saturday, the demonstrations against the regime in Iran continued.
Workers went on strike at the same time as violence broke out in several cities between police and protesters.
At least two people are said to have been killed during the day in two different incidents.
The protests are now in their fourth week.
They began after 22-year-old Mahsa Zhina Amini died after being arrested by the country's notorious morality police for allegedly breaking Iran's strict dress code for women.