The US treasury has been authorised to target firms and financial institutions conducting business with the North, writes BBC online Thursday.
The president said China’s Central Bank had instructed other Chinese banks to stop doing business with Pyongyang.
It comes less than two weeks after the UN approved new sanctions against the country over its latest nuclear test. President Trump singled out the North’s textiles, fishing, information technology and manufacturing industries.
Meanwhile, South Korea’s president, Moon Jae-in, said his country did not want the North to collapse.
The latest UN sanctions – which came after the North’s nuclear test on 3 September – restrict oil imports and ban textile exports, in an attempt to starve it of fuel and income for its weapons programmes.
It is the ninth round of UN sanctions to hit North Korea since 2006.
