The United States' draft resolution, which seeks to apply economic sanctions on the two warring countries if they fail to de-escalate a growing border conflict, was presented in New York on Monday to the five permanent members of the UN Security Council.
Speaking on condition of anonymity, a UN diplomat told Reuters that China wasn't willing to back the proposed amendment, which threatens economic and diplomatic sanctions under Article 41 of the U.N. charter.
The diplomat added that Russia was supporting the Chinese effort to water down the proposal.
The draft will be put before a Security Council vote on Wednesday.
The draft will probably change before it goes to a vote, the diplomat told Reuters.
The two began their latest conflict after South Sudan occupied the North's main Heglig oil field for 10 days last month. Although South Sudan left the oil field about a week ago, tensions remain between the two nations.
In a bid to prevent the conflict from escalating, the African Union has threatened to impose its own set of binding rulings on both sides if they fail to agree on deals related to a string of disputes within three months.
The African Union also asked the UN to pass a binding resolution demanding Juba and Khartoum comply with its declaration.