Around 30 Palestinians have been killed in the weekend surge of Israel-Gaza fighting
The American forces landed in the town of Busayra, east of Deir al-Zor, and "kidnapped a number of civilians", it said.
There was no independent confirmation of the report.
The province of Deir al-Zor, along the Iraqi border, is a strategic supply route for Iranian-backed militias who regularly send reinforcements into Syria to support President Bashar al-Assad against insurgents seeking to topple his family rule.
US forces are deployed at a base in al-Tanf region, south of Deir al-Zor, as part of combat mission against Islamic State militants who continue to wage a low-level insurgency in Iraq and Syria.