In a statement on Friday, the State Council's Customs Tariff Commission said the USA was violating the rules of the World Trade Organization, and contradicting previous negotiations between Washington and Beijing.
"If the USA side adopts unilateral measures of protectionism and damages China's interests, then we will respond right away, and take necessary measures to resolutely safeguard our own legitimate rights and interests", Geng said.
Beijing also said "all economic and trade agreements reached by previous negotiations will be nullified at the same time". In one of those agreements, which was conditional on Trump not threatening new tariffs, China promised to buy $70 billion worth of USA agricultural and energy products - a trade-deficit reducing deal which Trump had prematurely hailed as a victory.
Trump has made a number of tariff-related threats.
China, the world's No 2 behind the USA, has pledged to retaliate on United States exports including soybeans and pork.
"I am concerned that these new tariffs will hurt American manufacturers, farmers, workers and consumers", he said.
China's Communist Party-linked newspaper the Global Times decried the U.S.as the "provocateur" Saturday in reporting the new Chinese measures.
The statement was issued after the United States president announced tariffs of 25 percent on $50 billion of Chinese imports, making good on a pledge to punish the alleged theft of U.S. intellectual property.
China's Commerce Ministry fired back in a statement, "The United States has kept changing its mind and now launched a trade war".
The administration did reduce the original list of 1,333 product categories to 888 product categories worth about $34 billion.
The country's Commerce Ministry said China will apply tariffs on U.S. goods at the "same scale and the same strength". China's interest in USA lobster has grown exponentially in recent years, and selling to China has become a major focus of the lobster industry.
The USTR announced a second list of 284 goods valued at $16 billion that will be subject to review and public comment before the penalties take effect.
Donald Trump's first announced that the United States would impose trade penalties on Chinese goods in March.
Trump recently hit USA allies including the European Union, Canada, and Mexico with tariffs on steel and aluminum imports.