In a state television interview Assad also said that a deal between Turkish President Tayyip Erdogan and Russian President Vladimir Putin to drive out the Kurdish-led YPG militia from a 30 km (19 mile) "safe zone" along the border was a "positive" step that would help Damascus achieve its goal.
"It might not achieve everything ... it paves the road to liberate this area in the near future we hope," said Assad, who has remained in power in Damascus through a more than eight-year-long civil war with the backing of Russia and Iran.
The U.S.-allied Kurdish YPG militia reached a deal with Damascus to take up positions near the border after U.S. President Donald Trump's announcement in early October that he was withdrawing American forces from northeast Syria. The YPG is the main fighting element of the Syrian Democratic Forces (SDF) that has beaten back Islamic State in the region.
The withdrawal paved the way for a Turkish offensive against the Kurds and left them feeling abandoned by the United States and forcing them to work a deal with Damascus to help them resist Turkish forces. Ankara views the YPG as a terrorist organization because of its links to Kurdish militants in southeastern Turkey.
Assad also said Trump's decision to keep a small number of U.S. troops in the Kurdish-held areas of Syria “where they have the oil” showed that Washington was a colonial power that was doomed to leave once Syrians resist their occupation as in Iraq.
But he said his country could not stand up to a great power such as the United States and that ending the presence of American troops on Syrian soil was not achievable soon.
Assad said Trump was the "best American president" for his "complete transparency" about intentions to maintain control of Syria's main oilfields in Deir al-Zor province.
U.S. troops have begun deployment in the province in coordination with the SDF to increase security and continue the fight against remnants of Islamic State, a U.S. military spokesman said on Thursday.
Diplomats say the U.S. decision to prevent oil fields from falling back to government control would deny Damascus millions of dollars of much needed revenues and ensure its Kurdish ally a main source of income to govern areas it controls.
The Kurds would not be asked to immediately hand over their weapons when the Syrian army enters their areas in a final deal with them that brings back state control to the large swathe of territory they now control, Assad said in the interview.
"There are armed groups that we cannot expect they would hand over weapons immediately but the final goal is to return to the previous situation, which is the complete control of the state," he said.
The commander of the Kurdish-led forces Mazloum Kobani has said the agreement with Damascus could pave the way for a political solution to be worked out later with the Syrian government, that could guarantee Kurdish rights in Syria.
But he insisted at this stage it was only to allow the deployment of Syrian troops across SDF stronghold areas along the border with Turkey in a move to thwart Ankara's plan to create a "safe zone."
Syria had a right to defend its territorial integrity against separatist Kurds who aspired to create a Kurdish state and rule over Arabs and other ethnic groups, Assad said.
Resentment against Kurdish dominated rule in eastern Syria has grown among the predominately Arab population, residents say.