The United States has imposed visa bans on 20 unnamed senior Ukrainian government officials believed to be responsible for the violent crackdown against protesters.
President Barack Obama has urged Ukraine to avoid violence against peaceful demonstrators or face consequences.
Ukrainian President Viktor Yanukovych has announced a “truce” amid the deadly street clashes that have sparked fears of civil war in the former Soviet republic and caused concern among world leaders.
Mr Yanukovych made the announcement after holding private talks with three anti-government leaders, and as the US and European Union considered imposing sanctions on Ukraine.
He said both sides agreed to “the start of a negotiations process aimed at ending the bloodshed (and) stabilising the situation in the country for the benefit of civil peace”.
Earlier, the US president said there would be “consequences if people step over the line”, which included the Ukrainian military not interfering in what “should be a set of issues that can be resolved by civilians”.
The US has done everything from handing sandwiches to protesters in Kiev to tough-talking over the phone as they try to get a handle on the escalating Ukraine crisis.
But so far their efforts have been frustrated, with fresh violence between riot police and anti-government protesters leaving scores dead and hundreds injured.
Secretary of State John said the situation is bad but there is room for dialogue and that it is up to Mr Yanukovych to decide the future of his country.
“President Yanukovych has the opportunity to make a choice. The choice is between protecting the people that he serves – all of the people – and a choice for a compromise and dialogue versus violence and mayhem,” Mr Kerry said from Paris on Wednesday.
“We believe the choice is clear, and we are talking about the possibility of sanctions or other steps with our friends in Europe and elsewhere in order to try to create the environment for compromise.”
The European Union has called a meeting of its 28 member countries to take place on Thursday.
Such is the chaos in Kiev that US Ambassador Geoffrey Pyatt, who has been active in trying to negotiate a solution, was left to direct traffic on Tuesday night after his car got stuck.
The protests began in late November after Mr Yanukovych turned away from a long-anticipated deal with the European Union in exchange for a $15bn (£900m) bailout from Russia.
In December, Assistant Secretary of State Victoria Nuland met with protesters in Independence Square, handing out food in a show of solidarity.
A month later, she was embroiled in controversy as she was caught using an expletive while discussing the EU policy on Ukraine.
“F*** the EU,” she is heard saying during a phone conversation with Mr Pyatt, which was leaked on the Internet.
The remark caused embarrassment in Washington, even as officials tried to play it down, and exposed differences with the EU over how to manage the crisis.
It also escalated a war of words with Russia.
Moscow has accused the US of meddling in Ukrainian affairs.
Washington “offers numerous instructions for what the Ukrainian government should do next”, the state-run news agency Ria Novosti said.
Both the West and Russia are eager to gain influence over this former Soviet republic, a nation of 46 million people.
While Kiev and western Ukraine have risen up against Mr Yanukovych, he remains popular in the Russian-speaking eastern and southern regions, where economic and cultural ties with Russia are strong.
