In a statement, China's Foreign Ministry said China has "decided to design the entire category of fentanyl-type substances as controlled substances and begin the process of revising the relevant laws and regulations."
China and the United States have "agreed to take active measures to enhance law enforcement and narcotics control cooperation," including control of fentanyl-type substances.
The new term for the synthetic opioid drug means that people in China who sell fentanyl to the US "are subject to the laws of China's maximum punishment," the White House said.
Trump and Xi met for dinner at the G20 summit in Buenos Aires on Saturday.
Fentanyl, an extremely potent drug, is 50 to 100 times more effective than morphine and 30 to 50 times more effective than heroin.
According to the US Centers for Disease Control and Prevention, 5,500 people died in 2014 on synthetic opioid overdoses, most of them related to fentanyl. This is an increase of 80% over the number of deaths reported in 2013. Last year, the Drug Enforcement Administration issued a national warning stating that "drug-related drug overdose and fentanyl overdose are occurring at an alarming rate." In 2013, the Drug Enforcement Administration conducted 942 fentanyl seizures. In 2014 it made 3,344.
"It is outrageous that the toxic synthetic heroin fentanyl from China is pouring into the US postal system, we can and must STOP NOW! The Senate should insist on the STOP-ACT and prevent this poison from killing our children and destroy our land, no more delay! "said the tweet.
Yu Haibin, a high-ranking official at the National Narcotics Control Commission, told a press conference at the time that Trump's comments were "unacceptable" and "irresponsible." The country comes from China, "he said "It is highly irresponsible to draw such a conclusion on the basis of a few isolated cases."
Washington officials believe that China is the main source of fentanyl found within US borders.
Trump declared the opioid crisis last year to be a public health emergency in the United States and addressed Xi when the two leaders met in Beijing in November 2017.
Kevin Bohn and Steven Jiang of CNN contributed to this report.