Saturday's blast took place in the Shahid Rajaee section of the port, Iran's biggest container hub, shattering windows for several kilometres around, tearing metal strips off shipping containers and badly damaging goods inside, state media said.
Fires kept breaking out in different parts of the affected area as of Sunday night, according to state media, with helicopters and fire fighters continuing efforts to extinguish them.
Chemicals at the port were suspected to have fuelled the explosion but the exact cause was not clear and Iran's defence ministry denied international media reports that the blast may be linked to the mishandling of solid fuel used for missiles.
A spokesperson for the ministry told state TV the reports were "aligned with enemy psyops," saying that the blast-hit area did not contain any military cargo.
The Associated Press cited UK security firm Ambrey as saying the port in March had received sodium perchlorate, which is used to propel ballistic missiles and whose mishandling could have led to the explosion.
The Financial Times newspaper reported in January the shipment of two Iranian vessels from China containing enough of the ingredient to propel as many as 260 mid-range missiles, helping Iranian forces to replenish their stocks following their direct missile attacks on its arch-foe Israel in 2024.
New videos emerged on Sunday showing an apocalyptic scene at the still-smouldering port.
A crater that appeared metres deep sat surrounded by burning smoke so dangerous that authorities closed schools and businesses in the area.
Containers appeared smashed or thrown as if discarded toys, while the burned carcasses of trucks and cars sat around the site.
"We have to find out why it happened," Pezeshkian said during a meeting with officials broadcast on Iranian state TV.
By early afternoon, the head of Iran's Red Crescent Society told state media the fire was 90 per cent extinguished and officials said port activities had resumed in unaffected parts of Shahid Rajaee.
A spokesperson for the country's crisis management organisation appeared on Saturday to blame the explosion on poor storage of chemicals in containers at Shahid Rajaee, adding that earlier warnings had highlighted potential safety risks.
Government spokeswoman Fatemeh Mohajerani cautioned against "premature speculation," saying final assessments would be shared after investigations.
Negligence has often been blamed in a series of deadly incidents that have hit Iranian energy and industrial infrastructure in recent years.
"Did we really have to hold the container here for three to four months... until we had 120-140 thousand containers stored in this place?," Pezeshkian said after arriving in Bandar Abbas on Sunday.
Incidents in the country have included refinery fires, a gas explosion at a coal mine and an emergency repair incident at Bandar Abbas that killed one worker in 2023.
Iranian authorities have blamed some other incidents on Israel, which has carried out attacks on Iranian soil targeting the country's nuclear program in recent years and last year bombed Iran's air defences.
with AP
