The U.S. measures would initially hit Chinese entities considered "low-hanging fruit," including smaller financial institutions and "shell" companies linked to North Korea’s nuclear and missile programs, said one of the officials, while declining to name the targets.
The timing and scope of the U.S. action will depend heavily on how China responds to pressure for tougher steps against North Korea when U.S. and Chinese officials meet for a high-level economic dialogue in Washington on Wednesday, the administration sources told Reuters.
President Donald Trump and his top aides have signaled growing impatience with China over North Korea, especially since Pyongyang last week test-launched its first intercontinental ballistic missile, which experts say could put all of Alaska in range for the first time.
U.S. officials have also warned that China could face U.S. trade and economic pressure - something Trump has held in abeyance since taking office in January - unless it does more to restrain its neighbor.
The so-called "secondary sanctions" now being considered are a way for the United States to apply targeted economic pressure on companies in countries with ties to North Korea by denying them access to the U.S. market and financial system.
Word of the sanctions plan comes as U.S. ambassador to the United Nations Nikki Haley seeks to overcome resistance from China and Russia to a U.N. Security Council resolution imposing stiffer international sanctions on Pyongyang.
The targets now being weighed for sanctions would come from a list of firms numbering “substantially more than 10” that Trump shared with Chinese President Xi Jinping at a Florida summit in April and which U.S. experts have continued to compile for review, according to one of the officials.
"The president is losing patience with China," the official said, adding that there would be a "more aggressive approach to sanctioning Chinese entities ... in the not-too-distant future."
China's embassy in Washington did not respond immediately to a request for comment. The White House declined comment.
Though the sources stressed that no final decisions had been made, they said China, North Korea's main trading partner, was crucial to pressuring Pyongyang to prevent it from achieving the capability of striking the United States with a nuclear-tipped missile.
During a U.N. Security Council meeting last week, Haley threatened secondary sanctions if the council could not agree on new sanctions – though she did not cite China by name.
Reflecting growing concern about North Korea on Capitol Hill, two members of the U.S. Senate Banking Committee, Democrat Chris Van Hollen and Republican Pat Toomey, announced on Wednesday they would soon introduce legislation for North Korea modeled on the Iran secondary sanctions laws passed by Congress.