Debra and Marc Tice said in Beirut they had not heard from their son Austin since Aug. 13, The (Beirut) Daily Star reported.
"We are here today to appeal for information about Austin. Is he well, how can we contact him, and how can we return him to our family?" Marc Tice asked.
Austin Tice, 31, crossed into Syria in May via Turkey to report on the conflict for several newspapers, including The Washington Post.
His family said they had received no information on his whereabouts, or whether he is being held captive.
"Anyone who hears this and has any information, especially what we can do to help him, please contact us," Marc Tice pleaded.
In September, video apparently showing Tice surrounded by several armed men shouting "Allahu akbar [God is great]" was uploaded to YouTube.
Tice's parents said the video had given them no indication of where their son was being held and they have doubts about the video's authenticity.
U.S. State Department spokeswoman Victoria Nuland has previously said Tice is believed to be held by the Syrian regime.