The US secretary of state has said that some Chinese entities are failing to comply with international sanctions against Iran.
Hillary Clinton said the US was pressing very hard on the issue with the Chinese leadership.
Speaking on US network ABC, Mrs Clinton said the country was also considering further unilateral sanctions.
Her comments came as US President Barack Obama hosted a visit by Chinese President Hu Jintao, in Washington.
Analysts say Mr Hu’s four-day visit is the most important by a Chinese leader in 30 years given China’s growing military, economic and diplomatic clout.
“We think that there are some entities within China that we have brought to the attention of the Chinese leadership that are still not, shall we say, as in compliance as we would like them to be,” Mrs Clinton said.