The rapprochement between Riyadh and Tehran is part of a major regional realignment, amid rising tensions between Iran and Israel.
Tunisia reinstated a limited diplomatic mission to Syria in 2017, in part to help track more than 3,000 Tunisian militants fighting in Syria.
Prince Faisal bin Farhan Al Saud said that isolating Syria was not working and that dialog with Damascus was needed.
Legal representatives for the Iraqi, Jordanian, Palestinian, Libyan, Egyptian, and Emirati houses of representatives traveled to Syria to meet with Assad.
Syria's Assad is making outreach to Turkey via Moscow now that it knows China and Moscow can't help to rebuild Syria fast enough.
A Syrian return to the Arab fold and an easing of sanctions appear possible in the wake of the devastating earthquake, experts say.
Washington called on Syrian President Bashar Assad to grant immediate access to humanitarian assistance to all those in need, without exception.