"There is no satisfactory plan that is put before us concretely yet," Erdogan told a parliamentary meeting of his AK Party, RIA Novosti reported.
"Of course we are loyal to our agreements, our promise is a promise. But our patience is not limitless," he stated.
"If the terrorists do not leave Manbij in a few weeks, then our patience will end. The United States must keep Turkey's data on Syria's promises, otherwise Ankara itself will take steps to eliminate the threats to national security," he stressed.
Turkey wants Syria's Manbij to be cleared of the US-backed Kurdish People's Protection Units (YPG) which Ankara considers a terrorist group.
In December, the YPG announced its withdrawal from Manbij and called on Damascus to take control of the city to protect the area in the event Ankara launched a military operation against the Kurds.
In early June, US Secretary of State Mike Pompeo and Turkish Foreign Minister Mevlut Cavusoglug agreed on a roadmap related to the pullout of YPG forces from Manbij in order to maintain stability in the area.
In January, Erdogan said, following a phone conversation with US President Donald Trump, that Trump had proposed creating a 30-kilometre (18-mile) buffer zone in Syria.