Washington on Saturday called on Tigrayan rebels to withdraw from the Amhara and Afar regions in northern Ethiopia where fighting has intensified.
A statement from the State Department also urged the Tigray People's Liberation Front (TPLF) to "halt its advances in and around the cities of Dessie and Kombolcha."
Tigrayan rebels said Saturday they have secured "full control" of the strategic northern Ethiopian city of Dessie, sparking a furious denial by the government even as residents reported a retreat by federal forces from the area.
The rebels' capture of Dessie marks a new step in their offensive in the nearly year-long war, after they retook most of Tigray from federal forces in June and expanded their presence into neighboring regions.
"We urge the TPLF not to use artillery against cities and recall our strong objections to the ENDF airstrikes in Mekelle and other areas of Tigray which have cost countless lives," State Department spokesperson Ned Price said in the statement, referring to the Ethiopian National Defense Force.
"There is no military solution to this conflict, and all parties must begin ceasefire negotiations without preconditions."
Dessie, which is located in the Amhara region neighboring Tigray, lies about 400 kilometers (250 miles) north of the Ethiopian capital Addis Ababa.
Residents had earlier reported a heavy military build-up in the area, as civilians fleeing conflict-hit towns farther north poured into Dessie seeking refuge.
Much of northern Ethiopia is under a communications blackout, and access for journalists is restricted, making battlefield claims difficult to verify independently