China called for restraint on all sides after Russian President Vladimir Putin ordered an attack on Ukraine, while saying the military operation should not be described as an "invasion".
Mr Putin announced the launch of a major military offensive and ground troops crossed into the country from several directions on Thursday, with explosions heard in Ukraine's capital, Kyiv.
"China is closely watching the latest situation and we call on all parties to maintain restraint and prevent the situation from getting out of control," foreign ministry spokeswoman Hua Chunying said at a regular press briefing where she was repeatedly asked if Beijing condemned the actions.
Beijing has trod a cautious line on Ukraine as Moscow massed thousands of troops on the borders and criticised the West for new sanctions after Russia ordered troops into two breakaway Ukrainian regions it now recognises as independent.
Ms Hua on Thursday refused to call the military action an "invasion", labelling the term "prejudiced", and dodged questions on whether China was in contact with Russian and Ukrainian leaders.
"The Ukraine issue has a very complicated historical background" and was the result of "various factors," Ms Hua told reporters.
China has blamed the United States and its Western allies in recent weeks for "hyping up" the crisis, with Ms Hua saying at an earlier briefing on Wednesday that the US was "adding fuel to the fire".
The Chinese embassy in Ukraine on Thursday warned its citizens to be alert for "severe disturbances" and to stay home as much as possible.
