News reports had raised hopes that tension was easing on Friday by saying North Korean leader Kim Jong-il had told China's special envoy Tang Jiaxuan this week that his country planned no further nuclear tests.
Rice met Tang in person in Beijing on Friday and then told reporters travelling onwards to Moscow with her that he had given no sign China had achieved such a diplomatic breakthrough.
"Tang did not tell me that Kim Jong-il either apologised for the test or said that he would not ever test again," she said.
Russia is the last stop on Rice's five-day trip, aimed at shoring up support for UN economic and weapons sanctions imposed on Pyongyang a week ago to punish it for conducting an underground nuclear test on October 9.
Rice played down news reports that Kim had told Beijing he "regretted" the test, which was condemned internationally, including by China, the North's closest ally and economic lifeline.
"The North Koreans, I think, would like to see an escalation of the tension"
Condoleezza Rice, US secretary of state
"The Chinese did not, in a fairly thorough briefing to me, say anything about an apology," she said. "The North Koreans, I think, would like to see an escalation of the tension."
She also questioned whether Pyongyang intended to return to six-party talks, which have been stalled for nearly a year.
Kim Kye-gwan, North Korea's top nuclear negotiator, earlier told a US television Pyongyang hoped to return to the table.
Rice said before leaving China that North Korea's tone was still belligerent.
Rice's visits to Tokyo, Seoul and Beijing were overshadowed by speculation that the unpredictable communist state would conduct a second nuclear test.
On Friday, reports that Kim had told Tang no more nuclear tests were planned had raised hopes that the crisis was cooling.
South Korea's Yonhap news agency quoted a diplomatic source as saying: "I understand he (Kim) expressed clearly there was no plan to conduct nuclear tests."
Rice won few commitments from China and South Korea on implementing the restrictions on their defiant neighbour.
China, a traditional ally of North Korea, is seen as having the greatest potential leverage over Pyongyang, but it also fears instability and a potential wave of refugees should sanctions against North Korea prompt its collapse.