Earlier this week, US President Barack Obama has pledged to increase pressure on Russia.
The United States warned Russia on Thursday that it is mulling fresh sanctions over the fighting in Ukraine and welcomed an European Union (EU) move to broaden existing measures imposed on Moscow.
State Department spokeswoman Jen Psaki said the agreement by the EU foreign ministers to expand existing European sanctions "is just a further sign that the actions of the last several days and weeks are absolutely unacceptable and that there will be new consequences put in place."
The move in Brussels, where EU foreign ministers were meeting, was "building on a large sanctions effort that's been going on for months now," Psaki said, dubbing Thursday's announcement a "positive step."
She had no prediction about when the next round of US sanctions would come into force, or who would be targeted.
"Sometimes we add names, sometimes we add sectors or companies, and that's the same thing for the EU," Psaki said.
"We'll continue to consider others that we could add."
Earlier this week, President Barack Obama pledged to increase pressure on Russia and, in cooperation with US allies including Europe, to look at other options to tackle the issue.
"We will continue to take the approach that we have taken in the past, which is to ratchet up the pressure on Russia, and I will look at all additional options that are available to us, short of military confrontation, and try to address this issue," he said.