President Hassan Rouhani visited the site of the collapsed Plasco high-rise in downtown Tehran to inspect the ongoing search and rescue operation there.
Speaking to reporters on Saturday morning, Rouhani stressed that the search and rescue operation should continue until those trapped under the rubble are saved.
Up to 30 people, all of whom were most likely firefighters, are believed to be trapped under the rubble of the building, which caught fire early on Thursday and came down hours later.
Rescuers have been using life detection devices to locate possible survivors and, according to Mehr News Agency, at least four responses have been picked up, likely indicating that at least four people are still alive.
"We are very concerned for those who have been trapped under debris," Press TV quoted said Rouhani as saying.
"We hope we will have some survivors. This can be a lesson and a warning for all the officials to provide more safety for all citizens. This is a civil right of all people."
Rouhani expressed condolences to those who have lost loved ones in the incident and praised the firefighters and rescue teams for putting their lives at risk to rescue others.
He underlined the need to take measures to compensate business owners and workers who used to work at the building, which served as a trade center, for their material loss and the loss of income.
There were 560 business outlets and clothing production workshops in Plasco, of which only 100 had insurance coverage. Nearly 3,000 people have lost their jobs as a result of the building's destruction.
The Plasco building was Iran's oldest high-rise. Rising 17 stories above the ground, it had been built in the early 1960s and was the country's tallest building at the time of construction.
Rouhani also touched on the need for "comprehensive plans" to reinforce old structures across the country.
"We can get entrepreneurs, investors and banks onboard to help renovate these buildings … The plan is underway and it needs to be materialized."
Rouhani was accompanied in the visit by several ministers, advisers and other senior officials.
The government declared Saturday a day of national mourning and its embassies across the world lowered the flags to half-mast.
Iranian officials have yet to offer definitive casualty figures for the Thursday disaster.
