TOLUCA (AFP) - US President Barack Obama on Wednesday warned of "consequences" over the violence in Ukraine and said it held the government responsible for ensuring that its people can protest "without fear of repression."

"We hold the Ukrainian government primarily responsible for making sure that it is dealing with peaceful protesters in an appropriate way, that the Ukrainian people are able to assemble and speak freely about their interests without fear of repression," Mr Obama said during a visit to Mexico.

"I want to be very clear as we work through these next several days in Ukraine that we're going to be watching closely and we expect the Ukrainian government to show restraint, to not resort to violence in dealing with peaceful protesters," he said.

Mr Obama added that the United States also expects protesters to remain peaceful in the wake of violence in Kiev that left at least 26 people dead.

"We'll be monitoring very closely the situation, recognizing that with our European partners and the international community, there will be consequences if people step over the line," the US leader said.

"And that includes making sure the Ukrainian military does not step into what should be a set of issues that can be resolved by civilians."

The crackdown on anti-government protests by security forces on Tuesday triggered a storm of international condemnation, with the European Union convening urgent talks to mull possible sanctions.