The official told SANA that the Assad-aligned Syrian Arab Army would thwart the "conspiracy, end the presence of the US, its agents and tools in Syria, establish full control over the entire Syrian territory and preserve the country's sovereignty."
The US maintains some 2,000 troops in Syria and has said its forces will continue to back local anti-ISIS forces there until the extremist group is defeated and the area is stabilized.
The Syrian statement comes after the US-led coalition fighting ISIS announced plans Sunday to boost border security in the region, a move that Syrian and Turkish officials have said would destabilize the region.
"The Coalition is working jointly with the Syrian Democratic Forces to establish and train the new Syrian Border Security Force (BSF). Currently, there are approximately 230 individuals training in the BSF's inaugural class, with the goal of a final force size of approximately 30,000," a spokesman for the US-led coalition, US Army Col. Ryan Dillon, told CNN in a statement.
The over 50,000-strong Syrian Democratic Forces are a mix of Kurdish and Arab fighters and have been the primary US-backed force fighting ISIS in Syria.
The Syrian official said the US decision "came within the framework of its destructive policies which aim at fragmenting the region, fueling tensions and conflicts and hindering solutions to its crises."
"The Ministry considered any Syrian citizen who takes part in the US-backed militia as a traitor to the Syrian state and people and will be treated as one, adding that these militias will hinder reaching a political solution to the situation in Syria," SANA reported.
Also on Monday, Turkish President Recep Tayyip Erdogan accused the United States
of "building an army of terror" on Turkey's border with Syria, state-run Anadolu reported.
Both Damascus and Ankara oppose the coalition's proposed border force because they view such trappings of statehood as helping to solidify the Syrian Democratic Forces' hold on the vast tracts of territory it has captured from ISIS east of the Euphrates river.
The coalition has stressed that the border force training is focused solely on security and not on other border activities like customs or immigration.
"This force is designed to establish security that supports the lasting defeat of ISIS, prevent the conditions under which it can re-emerge and restrict the flow of foreign terrorist fighters into Iraq, Turkey and Europe," Dillon told CNN on Monday.
The US has clashed with regime troops in the past, carrying out airstrikes against forces that were seen to pose a threat to a US base and shooting down a Syrian jet in June after it bombed Syrian Democratic Forces.
It is unlikely that the regime in Damascus possesses the capability to carry out its threat as a significant portion of its forces are fighting militants in the country's western province of Idlib.
"The Coalition remains focused on our support to the Syrian Democratic Forces in defeating remaining ISIS pockets in eastern Syria," Dillon said. "Coalition members are always prepared and have the inherent right to protect themselves against ISIS or any other threat."