A that broke out at an facility in southern was brought under control without causing any damage, according to local media.
"A fire has occurred in an open oil channel leading to the export port in the city of Mahshahr," Fars news agency reported after the Sunday incident.
Thick smoke filled the sky over the port, the agency stated.
Mahshahr is located in Khuzestan, an oil-rich province bordering Iraq.
The Tasnim agency described the fire as "minor", adding that there was no "human or financial loss".
A security manager at the port, quoted by the Rokna news website, said the fire was caused by technical failure in a lighting system near the open channel.
Mahshahr Governor Fereydoun Bandari said "firefighters prevented the fire from spreading to oil tanks at the export port", according to Fars.
The cause of the incident is under investigation, he added.
It occurred following weeks of protests in Iran after the September 16 death of Mahsa Amini, a 22-year-old Iranian Kurd, three days after her arrest by vice police.
In a separate incident in the same city, Iran's Islamic Revolutionary Guard Corps said Sunday its forces had killed an "element hostile to the revolution" after an attack on a military base in Mahshahr.
"The forces fired on two terrorists on motorbikes in order to protect the headquarters, killing one of them while steps were taken to identify and arrest the second person," the IRGC said in a statement.
Iran has the world's second largest gas reserves, after Russia, and the world's fourth largest oil reserves, but is under strict US sanctions which have restricted exports and isolated it from the global financial system.