Ahmed Bin Hilli, deputy secretary-general of the organization, told Russia's Interfax news agency discussions were continuing in regard to adding Iran to the Syria Contact Group, a move that he favored.
"In my view, all the players taking part in the Syrian crisis must be part of this contact group," Hilli said.
The next scheduled meeting of the Syria Contact Group is June 30 in Geneva.
Mideast Online said Hilli urged Russia to cut off arms shipments to Damascus, saying "any assistance to violence must cease."
Hilli also called for a strengthening of the mandate of Kofi Annan, the special envoy to Syria of the United Nations and the Arab League.
"To make this plan work, we need to find a new mechanism and the mandate of the special envoy must be reassessed, so we can be sure that all the sides are observing the plan," he said.