The list of proposed designations mirrors new sanctions announced by the U.S. Treasury last week.
The United States made the proposal to the 15-member U.N. Security Council North Korea sanctions committee, which operates by consensus.
Russia objected to the designations because it said the U.S. proposal was not "adequately substantiated by sufficient information," diplomats said. China gave no reason for its objections.
Russia and China have suggested the Security Council discuss easing sanctions after U.S. President Donald Trump and North Korean leader Kim Jong Un met for the first time in June and Kim pledged to work toward denuclearization.
The United States and other council members have said there must be strict enforcement of sanctions until Pyongyang acts.
Last week, Washington imposed sanctions on Moscow-based Agrosoyuz Commercial Bank, North Korean banker Ri Jong Won, China-based Dandong Zhongsheng Industry & Trade Co Ltd and North Korea-based Korea Ungum Corporation.
The U.S. Treasury Department said Agrosoyuz Commercial Bank had conducted "a significant transaction" for North Korean banker Han Jang Su, who had been blacklisted by Washington. Han is the Moscow-based chief representative of Foreign Trade Bank (FTB), North Korea's primary foreign exchange bank.
The Security Council blacklisted FTB in August last year. Ri is FTB's deputy representative in Moscow.
The U.S. Treasury said Dandong Zhongsheng Industry & Trade and Korea Ungum Corporation were FTB front companies.
The U.N. blacklist would impose a global travel ban and asset freeze on those designated.
Russia and China last month delayed a U.S. push for the Security Council sanctions committee to order a halt to refined petroleum exports to North Korea, asking for more detail on a U.S. accusation that Pyongyang breached sanctions, diplomats said.
Sanctions by the United States and the U.N. Security Council, which include a ban on exports of coal, iron, lead, textiles and seafood from North Korea, and caps on imports of oil and refined petroleum products, are aimed at choking off funding for Pyongyang's nuclear and ballistic missile programs.
(Reporting by Michelle Nichols; additional reporting by Eric Beech in Washington; editing by Diane Craft)