According to a report published in al-Riyadh newspaper on Friday, Samer Lababidi was taken into custody the previous day after he flashed the victory sign in his Facebook picture following the recapture of Aleppo by the Syrian army soldiers and their allies.
The man, who is in his forties, faces accusations of publishing statements related to the war on Syria, the report added.
Saudi authorities deactivated Lababidi's Facebook account after his detention.
The arrest comes as the Riyadh regime has been a supporter of militants fighting against the Damascus government since 2011, when the conflict broke out in the Arab country.
Takfirism, which is trademark of many terrorist groups operating in Syria, is largely influenced by Wahhabism, the radical ideology dominating Saudi Arabia and freely preached by Saudi clerics.
In a video statement published on the Syrian presidency's Twitter account on Thursday, Assad offered felicitations to the Arab nation on the liberation of Aleppo, saying it was "history in the making and worthy of more than the word 'congratulations'.”
Irked by Syria’s recapture of Aleppo, Ahmad bin Abdulaziz Qattan, the Saudi ambassador to Egypt and the kingdom’s permanent representative to the Arab League, said Riyadh will continue to support the militants until the government of Syrian President Assad is toppled.