Ukrainian opposition leaders have rejected President Viktor Yanukovych’s offer of talks, saying they insist on the government's resignation.
Protesters continue to occupy sites in central Kyiv, including City Hall, after riot police withdrew December 11 following an aborted attempt to clear the streets. Arrests and some scuffles were reported in the confrontations.
In Washington, the Pentagon said Defense Minister Pavlo Lebedev had told Defense Secretary Chuck Hagel that Yanukovych's government would not use the Ukrainian armed forces against demonstrators.
A Pentagon statement said Hagel, in a telephone call with Lebedev, warned against use of armed forces against the civilian population “in any fashion.”
The statement said Hagel “underlined the potential damage of any involvement by the military in breaking up the demonstrations,” and called for restraint.
The U.S. State Department, meanwhile, said sanctions against Ukraine's government are an option.
Spokeswoman Jen Psaki said that Washington has been discussing a response to the Ukrainian unrest with European leaders and the International Monetary Fund (IMF).
Opposition leaders Arseniy Yatsenyuk and Oleh Tyahnibok said they would not hold talks with Yanukovych until their demands, including that he resign, were met.
Yatsenyuk added that it was not for Ukrainian authorities to set the time and place for discussions.
"When it comes to talks [with Ukrainian authorities], it's not for political leaders to decide but for the people who are standing in the Independence Square to decide," he said. "We should take the mandate from the people to hold any talks."
Earlier on December 11, Yanukovych had met with top EU and U.S. envoys.
Afterwards, the EU's foreign-policy chief Catherine Ashton said Yanukovych had promised to take steps toward solving the crisis in Ukraine within 24 hours.
Ashton said she emphasized in her talks with Yanukovych that using police to end the protests, as happened late on the evening of December 10, was counterproductive to reaching an amicable solution to Ukraine's current unrest.
"We've had some discussions, of course, about what happened last night [December 10]," she said. "I made it perfectly clear that this is not the way to go forward. I made it perfectly clear that we expect to see discussion and dialogue with people who are using their right to assembly, to make a peaceful demonstration and that any action that provokes a situation, intimidates people, is most likely to result in more people feeling that they want to participate."
Earlier, U.S. Assistant Secretary of State Victoria Nuland told Yanukovych that police actions against protesters were "absolutely impermissible" in a democratic society.
Nuland told reporters after meeting Yanukovych in Kyiv that she had had "tough but realistic talks," which lasted for more than two hours.
Nuland added that Washington believed it "is still possible to save Ukraine's European future, and that's what we want to see the president lead. That's going to require immediate security steps and getting back into a conversation with Europe and with the International Monetary Fund and bringing justice and human dignity to the people of Ukraine."
Thousands of Ukrainians have been out in the streets of Kyiv for three weeks, angry at Yanukovych's last-minute decision to spurn a landmark agreement with the European Union. The decision was apparently taken under pressure from Russia which opposed the deal and threatened trade repercussions.
"Roundtable" talks aimed at defusing the political crisis in the country were held in Kyiv on December 11, but opposition leaders did not take part. The talks were proposed by former Ukrainian President Leonid Kravchuk and backed by Yanukovych.
A first meeting took place on December 10, also without the participation of the opposition, which denounced the initiative as "orchestrated."
Earlier on December 11, former Ukrainian President Viktor Yushchenko said he would not participate.
He said the talks had been "compromised" by the overnight crackdown on pro-European demonstrators.
At around midnight on December 10, dozens of demonstrators and police were hurt in scuffles when hundreds of security personnel in riot gear moved in on the main protest camp on Kyiv's Independence Square and state buildings occupied by demonstrators.
Police later withdrew, and Interior Minister Vitaliy Zakharchenko vowed that there would be no forcible dispersal of protesters.
Opposition leader Vitaliy Klitschko said that with the overnight police action against protesters, Yanukovych had "closed off the path to any compromise."
The opposition called on Ukrainians to head to Independence Square to protect the protest camp.
On December 11, protesters on the square were putting back some of the barricades removed overnight by police.
With reporting by Reuters, Interfax, and AFP