Tehran has given foreign social media messaging applications one year to move the data they hold about Iranian users onto servers inside Iran.
The declaration on May 29 by Iran's Supreme Council of Cyberspace has prompted privacy and security concerns from Iranians who use social media.
Iran has some of the strictest controls on internet access and blocks access to social media like Facebook and Twitter.
But many Iranians have been able to circumvent the blockages and gain access foreign social media through special software.
But Iranian authorities have been increasing their crackdowns against social media users.
On May 16, Iranian police announced the arrest of eight people in an operation targeting Instagram and other social media users.
Those arrests involved photographers as well as women in Iran who posed for photographs with their hair uncovered – a taboo under Iran’s conservative Islamic laws.
