The measure, which SANA said was meant to "fortify national unity," comes as al-Assad faces mounting international pressure following the murder of former Lebanese prime minister Rafiq al-Hariri.
On Monday the UN Security Council passed a resolution ordering Damascus to cooperate fully with an international inquiry into the killing or face unspecified action.
Al-Assad has released hundreds of political prisoners since assuming power in 2000 but human rights activists say the Syrian authorities are still holding thousands of detainees under emergency law in force since 1963.
"This move gains the government more popularity and consolidates national unity in the face of the dangers facing Syria," Ammar Qurabi of the dissident Arab Organisation of Human Rights in Syria told Reuters.
Qurabi identified two of the prisoners freed under Wednesday's pardon as Ali Abdullah, detained in May for reading a statement by a London-based leader of the banned Muslim Brotherhood, and Mohammad Radoon, head of the Arab Organisation of Human Rights in Syria, arrested earlier this year.
Al-Assad introduced a measure of political freedom in Syria after succeeding his late father Hafiz al-Assad, but critics say the authorities have since cracked down again on dissidents.