He added that fighters also captured the nearby al-Izba gas field.
The Syrian Democratic Forces, which are backed by the USA, are fighting Islamic State forces in Deir Ezzor from the east while the Syrian regime and its allies approach the city from the west.
"We need to know where they are, and they need to know where we are" in the in Deir al-Zour area, Army Col. Ryan Dillon, a spokesman for Combined Joint Task Force-Operation Inherent Resolve, said.
According to a new report from Axios, representatives of the US and Russian governments recently met "somewhere in the Middle East" to hold secret talks that aren't so secret anymore.
Russia's warning underscored rising tensions over Syria between Moscow and Washington.
The U.S. -backed militias said on Saturday they had come under attack from Russian jets and Syrian government forces, something Moscow denied.
Russia's Defense Ministry said on Tuesday that the waters of Euphrates rose as soon as the Syrian army began crossing the river.
Syrian troops supported by Iranian-backed militias have also crossed to the eastern side of the river, increasing their presence in an area where USA -backed militias have also advanced.
Days before that, the Syrian army had broken through Islamic State lines and reached an enclave held by the government in Deir al-Zor.
On the eastern bank of the Euphrates River, the reporter said that the army units, in cooperation with the allies reestablished full control over the village of Mazloum and some strategic sites in the town of Khasham after carrying on severe clashes with the ISIL terrorists, killing and injuring a number of them.
"According to our information, USA intelligence services initiated the offensive to halt the successful advance of government troops to the east of Deir al-Zor", said Colonel-General Sergei Rudskoi.