US Secretary of State Condoleezza Rice has warned North Korea it faces "other options" if it does not co-operate in six-nation talks on its nuclear plans.
Ms Rice hopes China will use its influence on Pyongyang
She was speaking in China at the end of a Asian tour that has focused on Pyongyang's nuclear ambitions.
Ms Rice also said a new Chinese law targeting Taiwan secession highlighted the risk of the EU's plan to lift its arms embargo on China.
The EU imposed the embargo after the 1989 Tiananmen Square massacre.
Ms Rice appealed to China to reduce tensions with Taiwan, which Beijing sees as part of its territory.
"The anti-secession law was not a welcome development because anything that is unilateral that increases tensions, which clearly, the anti-secession law did increase tensions, is not good," Ms Rice told journalists after talks with Chinese leaders.
But the focus of Ms Rice's visit was North Korea, and how China, as its closest ally, could use its influence to persuade Pyongyang to return to the talks table.
Last month the North pulled out of six-party talks - hosted by China - on its nuclear programme.
Ms Rice indicated that Washington's patience with North Korea was limited.
If North Korea failed to co-operate, "then of course we'll have to look at other options", she said.
She did not specify these options, but stressed: "We have no intention to attack."
Analysts believe the options could include seeking international sanctions through the United Nations Security Council.
But it is likely that Beijing would prefer to resolve the crisis through dialogue.
On Sunday President Hu told Ms Rice that China was willing to work with the other parties to make it possible for the talks to resume at an early date, Chinese media reported.
It is a commonly held belief outside China that it holds the key to North Korea, says the BBC's Rupert Wingfield-Hayes in Beijing.
The logic is simple, he says - without Chinese grain, oil and coal, North Korea's economy would collapse.
But China has said it had limited influence and the US should be more flexible.
Ms Rice also raised her host's human rights record, saying progress had taken place, but "we expect progress to continue".
Last week, Washington announced that it would not be sponsoring a resolution condemning China at the UN human rights commission in Geneva.
Soon after the announcement, it was confirmed that China had released a prominent Uighur dissident, Rebiya Kadeer.
Ms Rice has now departed Beijing, following a week-long trip that has also taken her to India, Afghanistan, Pakistan, Japan and South Korea.