WASHINGTON - The White House threatened on Sunday to slap sanctions on Ukraine "in response to its use of violence" against protesters.
"The US will continue to consider additional steps -- including sanctions -- in response to the use of violence," National Security Council spokeswoman Caitlin Hayden said in a statement.
"We are deeply concerned by the violence taking place today on the streets of Kiev and urge all sides to immediately de-escalate the situation," she added.
Protesters on Sunday attacked riot police with sticks, fireworks and smoke bombs in central Kiev, Ukraine's capital, triggering another wave of clashes.
According to Ukraine's media reports, the protesters have tried to overturn one police car and torched another interior forces vehicle, which met with strong resistance from the police.
No causalities in the clashes have been officially confirmed so far. Urainian police has opened a criminal case into the incident.
The latest wave of protests came after the Ukrainian parliament approved a legislation on Thursday, banning some type of demonstrations. The bill is widely seen as "anti-protests law" and has sparked public criticism.
"The increasing tension in Ukraine is a direct consequence of the government failing to acknowledge the legitimate grievances of its people," Hayden said, urging the government to repeal the bill, withdraw the riot police from Kiev, and start a dialogue with the opposition.
In his first response to the violence, Ukrainian President Viktor Yanukovych said on his website late Sunday that he has tasked a working group, headed by national security council head Andriy Kliuyev to "consider the issues regarding the settlement of political crisis."
Protests erupted in November after Ukraine backtracked on a partnership agreement with the European Union, a path toward an eventual membership of the bloc.
The US State Department said in December that sanctions on Ukraine were being considered.