Kenzo Oshima, the Japanese ambassador to the UN, said on Monday that discussions would be delayed while a high-level Chinese delegation was on a six-day visit to Pyongyang.
Meanwhile, in Washington, Condoleezza Rice, the US secretary of state, said that the US had also agreed with a Japanese proposal to postpone the vote.
The Chinese delegation, led by Hui Liangyu, the country's vice-president, arrived in North Korea on Monday amid hopes that the visit would ease rising tensions over last week's missile tests.
Rice said that the Chinese mission showed "some promise" and that Washington wanted to give it time.
North Korea launched at least six missiles early last Wednesday and fired off a seventh about 12 hours later.
The missiles included a long-range Taepodong-2, which some experts said could hit the US state of Alaska. US officials said it flew for less than a minute before falling into waters west of Japan.
China has also circulated a non-binding presidential statement in the security council as an alternative to an earlier draft resolution presented by Japan, with the backing of all Western members of the 15-member council.
"The Security Council has to take responsible, constructive and prudent action"
Wang Guangya, Chinese ambassador to the UN
Wang Guangya, China's UN ambassador, said the document provided the "best framework and the best format" for a "unified" response from the Security Council to North Korea".
The Chinese presidential statement contains many of the key elements in the Japanese document, including a call on member states to block the transfer of items to North Korea that could be used in missile and weapons of mass destruction programmes.
Both documents call on Pyongyang to return to the six-party talks and to implement its pledge to abandon all nuclear weapons and return at an early date to the nuclear Non-Proliferation Treaty (NPT).
But Emyr Jones Parry, Britain's UN envoy, said the Chinese document "just really didn't do the job" because "it did not respond sufficiently [or] robustly" to what the present threat actually was.
Wang said the key difference in his text was that he dropped the description of the North Korean missile tests as a "threat to international peace and security", as well as the draft's invocation of chapter seven of the UN charter.
Wang says the Chinese proposal
provides the best framework
Chapter seven, invoked in cases of threats to international peace and security, can authorise sanctions or even military action.
"The Security Council has to take responsible, constructive and prudent actions," Wang said.
Vitaly Churkin, the Russian envoy, said the text provided "an excellent basis for a strong signal to Pyongyang".
"We think what our Chinese colleagues have offered is the right mode of action," he said.
North Korea agreed in September to end its nuclear programme in exchange for security guarantees and aid, but walked out of six-party talks - with China, Japan, Russia, South Korea and the United States - two months later over US sanctions on a bank accused of laundering money for Pyongyang.