"We will make sure that all companies, be they Chinese- or foreign-owned, so long as they are registered in China, will be treated as equals", Li said.
Trump reacted on Twitter, promising "great and fast economic retaliation against China if our farmers, ranchers and/or industrial workers are targeted".
Trump sent two tweets on September 18 blaming China as both parties announced they would slap new tariffs on each other.
But, he said voters know China has been taking advantage of US trade for years. "They rebuilt their country with tremendous amounts of money pouring out of the United States and I've changed that around".
China hit back with tariffs of its own on US$50 billion of United States products and focused on the agriculture sector - punishing industries whose workers largely supported Mr Trump.
Trump warned on Monday that if China takes retaliatory action against USA farmers or industries, "we will immediately pursue phase three, which is tariffs on approximately $267 billion of additional imports".
The allegation added an explosive new element to the dispute after Trump pulled the trigger late Monday on 10 per cent tariffs against another $200 billion in Chinese goods from next week, with a threat of more tariffs on another $267 billion.
China's yuan, also known as the renminbi, has steadily depreciated this year, causing Trump to accuse Beijing of deliberately manipulating the currency to offset the new tariffs.
The United States may make a deal at some point, Trump said during a joint press conference with Polish President Andrzej Duda in the Oval Office on Sept 18. If the Chinese economy slows under the weight of US import taxes, the global economy might also stumble, according to Stephanie Segal, deputy director of the Center for Strategic and worldwide and Studies, a Washington think tank. Business leaders are warning the high-stakes strategy could upend their supply chains and raise costs, as economists worry Trump's tactics could derail the broadest global upswing in years.
China's trade practices have always been a source of frustration for USA companies, which are not able to gain access to parts of China's market and are forced to hand over valuable technology and trade secrets to Chinese partners in exchange for operating there.
The latest USA duties spared smart watches from Apple and Fitbit and other consumer products such as baby auto seats.
The clash between the world's top two economies is already hurting companies on both sides of the Pacific.
This week, Washington raised the stakes by saying it would impose new tariffs on $200bn (£152.1bn) worth of Chinese goods from Monday.
U.S. business leaders railed against Mr Trump's decision to issue new tariffs.
Premier Li Keqiang's comments add to Beijing's effort to portray itself as a defender of global trade and multilateralism in the face of complaints by Washington and other trading partners about industry policies they say violate its market-opening commitments. As counterintuitive as it might seem, the president sees this fact as ultimately helping USA workers. "We'll see what happens".
U.S. Commerce Secretary Wilbur Ross said on Tuesday the next step on holding "constructive negotiations" was up to China.
Mulloy believes that there is a strong bipartisan support for Trump's China tariffs.
Walmart's chief financial officer, Brett Biggs, said last month that "While we know questions persist about tariffs, the potential future impact is hard to quantify".