"The Chinese side is always opposed to unilateral sanctions, to the frequent implementation of unilateral sanctions, especially when it hurts interests of third parties," foreign ministry spokeswoman Hua Chunying said.

The administration of US President Donald Trump chose to stick by a nuclear deal between Iran and world powers on Wednesday and continue waiving sanctions related to its atomic activities.

But it balanced the decision with new measures against Iranian defence officials and a Chinese business linked to Iran's ballistic missile programme.

"We think (this kind of sanctions) are unhelpful in enhancing mutual trust and unhelpful to the international efforts to solve this issue," Hua said at a regular press briefing.

"We have lodged representations with the US side. We hope the US side can resolve their anti-proliferation concerns through dialogue and communication, and proceed according the principles of respect, equality and mutual benefits".

Hua said China strictly fulfils its international obligations and follows local policies and regulations related to non-proliferation issues.