The Pakistan Electronic Media Regulatory Authority (Pemra) issued an advisory on Wednesday warning television and radio stations against any Valentine's Day celebrations.
"No event shall be held at the official level or at any public place," Pemra said.
The ban was introduced by Islamabad High Court last year after a petition by a citizen who said the Feb 14 holiday was a cultural import from the West and "against the teachings of Islam".
More than 60 percent of the population of the Muslim-majority nation is aged under 30. Many young people and commercial establishments have in recent years embraced Valentine's Day hearts, flowers and chocolates.
But the country of 208 million has also seen a wave of ultra-religious political activism that has brought a backlash against such celebrations, which some call immoral.
"We're Muslims. Our religion forbids things like Valentine's Day," said Taufeeq Leghari, who was waiting for transport close to a florist's stall in Rawalpindi, adjacent to Islamabad.
Flower seller Salman Mahmod took a different view."I don't know what danger these Islamists would face if I earn a little more from selling flowers and someone can have a chance to celebrate something," he said.
Young people are not too afraid of the ban.
"I will celebrate," said 21-year-old university student Abid Ansari in Islamabad. "This is my choice."