"Security forces arrested the Iraqi suspect [on Saturday] while he was driving his car," the source said on condition of anonymity.
AFP reports that four suspects, including one Iraqi, were arrested late on Saturday in Amman in connection with the rocket attacks.
The Iraqi was one of four suspects being sought by authorities.
The source did not specify where the man was apprehended.
Three Katyusha rockets were fired from the port on Friday, one of them missing two US warships anchored nearby but killing a Jordanian soldier as it smashed into a warehouse. No US troops were harmed in the attack.
Another landed close to the airport in the adjacent Israeli
resort of Eilat. The third struck a site near a military hospital.
Rocket launcher found
Earlier, Jordanian authorities found the launcher that fired three Katyusha rockets from a hilltop warehouse.
Two other rockets were fired towards Israel from the same warehouse, which is in the hills on Aqaba's northern edge, about 8km from the port.
One rocket landed inside Israel
close to Eilat airport
"We have found the rocket launcher in the warehouse from where they fired," Jordanian Interior Minister Awni Yirfas said on Saturday in what marked one of the first breakthroughs in the investigation.
"The investigation is still under way, and issues related to it will remain secret so it would not harm the process," Yirfas said.
"I cannot give you the names or say if we are looking for the perpetrators in the desert or any other place."
Jordanian security forces are searching for six people, including one Syrian and several Egyptians and Iraqis, who are believed to have escaped in a vehicle with Kuwaiti licence plates after firing the rockets.
An al-Qaida-linked group, the Abdullah Azzam Brigades, said in an internet statement that it staged the attack, but the claim could not be authenticated.
King Abdullah, who was in Russia
for talks, condemned the attacks
The group was among several organisations that claimed responsibility for bombings in three Egyptian Sinai Peninsula resorts during the past year that killed around 100 people.
A mood of gloom has gripped the kingdom's economic and trade sector in the wake of the rocket attack, reports Aljazeera.
Concern is mounting that news of the attack could adversely affect Jordan's trade with the rest of the world, in view of the fact that Aqaba is the kingdom's only sea outlet.
The rocket attacks also caused international oil prices to rise on Friday despite Jordan not being an oil exporter.
King Abdullah II, who is expected to return to Jordan on Saturday after a state visit to Russia, condemned Friday's attacks.
"This criminal attack will not deter Jordan from carrying out the true message of Islam which terrorists are trying to distort," Abdullah said in a statement carried by the state-run Petra news agency.
The rocket firings deepened concerns about new militant activity in a sleepy corner of the Middle East usually known for beach vacations and Israel-Arab peacemaking.
Until last year, the Red Sea area including Egypt's Sinai had seen no violence, but since October the area has seen a series of attacks.
These include the Egyptian resort bombings in Sharm al-Shaikh and Taba and a recent roadside bomb blast in the northern Sinai that targeted a vehicle belonging to the Multinational Force and Observers, which is helping monitor the 1979 Egypt-Israeli peace deal.
One of Friday's rocket sailed over the USS Ashland's bow and hit a nearby Jordanian military warehouse that US forces use to store goods bound for Iraq.
The Ashland, an amphibious assault ship, had docked on 13 August with the helicopter carrier USS Kearsarge at Aqaba's port for joint exercises with Jordan's military.
Both vessels left after the attack as a precaution.
Jordanian officials have not commented on where they think the rockets originated nor who might have provided them.
US assault warships have left
Aqaba port for safety reasons
Hizb Allah pounded Israel's north with Katyusha rockets for two decades in a guerrilla war that ended with Israel's pullout from southern Lebanon in 2000 and still fires the rockets from southern Lebanon towards northern Israeli towns.
The group has tried to smuggle Katyusha rockets through Jordan into the bordering West Bank to be passed onto Palestinian fighters opposing Israel's occupation of the Palestinian territories.
Jordanian authorities arrested three Hizb Allah members carrying Katyusha rockets in December 2001 after they entered Jordan through Syria bound for the West Bank.
After intense diplomatic contacts by Hizb Allah leader Shaikh Hassan Nasrallah and Lebanese President Emile Lahoud, Jordanian authorities returned the three to Lebanon in May 2002.