The source said the four were captured on Thursday while travelling between Baghdad and Ramadi.
He had no information about the captors or for whom the drivers worked for.
However, relatives of two of the missing men said they were employed by Lebanon's al-Jubaili transit company.
The head of the Lebanese Truckers' Association said the drivers were taking electric generators from Lebanon to Iraq, to sell to Iraqi traders. He said they had no links with any of the occupation troops.
"They were supposed to arrive in Baghdad last night," Chafic al-Assis told Reuters. "Our office in Baghdad called this morning to say they didn't show up."
A family in north Lebanon identified two of the truckers as Nasir al-Jundi and Tarik al-Jundi, and said they had left Lebanon on Sunday. Other Lebanese drivers in Iraq called the family on Friday to say they had not arrived.
Relatives appealed for their release, saying the two had gone to Iraq only to earn a living.
A spokesman in Baghdad's Interior Ministry said the ministry was aware of the reports, but had no further information. There are now five Lebanese nationals last seen in Iraq.
Several Lebanese in Iraq have been taken captive and released in recent months. Some of their captors demanded ransoms or accused the men of working with the occupation forces. In June a Lebanese captive was killed.
Plea to free businessman
Meanwhile, about 3000 people, including Muslim and Christian leaders, gathered on Wednesday in Kobeyat, northern Lebanon to demand the release of a Lebanese businessman captured in Iraq.
During the rally, several speakers urged the Association of Muslim Scholars in Iraq to "carry out a good offices mission to obtain the release" of Antoine Antoun.
The Beirut-based People's Campaign for Support of Iraq and Palestine also issued an appeal for his release.
Antoun had planned to be in Lebanon on August 15 to prepare for his wedding. He was taken captive along with his Iraqi driver on Saturday by a group of 50 armed men who raided the factory he set up in Baghdad two years ago.