It comes as hundreds of international figures -- from Nobel laureates to actors -- pledged their "unwavering" support of protesters in Iran.
ADVERTISEMENTIran will continue to restrict access to Instagram and WhatsApp, the country's President Ebrahim Raisi announced on Wednesday.
The messaging and social media platforms have been blocked for several months, amid unprecedented anti-government protests.
Instagram and WhatsApp, which are both owned by Mark Zuckerberg's Meta, were the "origin of the insecurity... during the recent riots" in Iran, claimed Raisi.
The block comes on the same day hundreds of international figures issued a joint appeal, expressing their "unwavering" support of Iranians resisting the regime.
Sparked by the death of 22-year-old Mahsa Amini after she was arrested by police, Iran has been engulfed by a wave of unrest since September.
Iranian authorities responded ferociously to the demonstrations, blocking internet access and violently cracking down on protesters.
Raisi, a hard-line former jurist, recognised that the internet disruptions were causing "discontent" in his speech televised Tuesday evening.
Many Iranians have hoped for an easing of restrictions with the number of street protests on the wane, while those outside the country remain frustrated and concerned about the continued difficulty of contacting their loved ones.
In January, former government spokesman Ali Rabii warned that some "three million companies and the employment of 12 million people" depended on internet access.
Employees in Iran, including those inside government departments, have reported spending large amounts of time at work with nothing to do, amid the internet shutdowns.
Instagram and WhatsApp were the most used applications since Youtube, Facebook, Telegram, Twitter and Tiktok platforms were blocked in recent years.
Even before the protests, internet access in Iran was heavily restricted. However, huge numbers of Iranians use VPNs to access web pages hosted outside the country, through new restrictions have made it increasingly difficult to use the tools.
On Wednesday, 480 international figures -- from Nobel laureates to actors -- issued a statement stressing that protesters in Iran "deserve unwavering support from the lovers of freedom in the world".
Published by the US-based NGO Freedom House, they claimed: "the triumph of freedom in Iran could revive the global wave of democratization that was so strong at the end of the 20th century, but which has weakened in the face of the counter-authoritarian attack".
The global names -- including Nobel Prize-winning Belarusian writer Svetlana Alexievich, former US Secretary of State Hillary Clinton and actor Richard Gere -- emphasised their support of Iranian women.
They underlined that "the end of the Islamic Republic's system of misogyny would constitute a global turning point in the long march towards a world where women are treated equally".
Young women have played a pivotal role in the demonstrations that first focused on the strict Islamic dress codes in Iran, which are deeply unpopular among large sections of the population.
Amini was arrested for allegedly not wearing her headscarf properly and sporting skinny jeans.