Speaking at the opening of the annual meeting of China's parliament, Mr Li said Beijing stood by the "one China" principle, which states that Taiwan is part of China.
In response to Mr Li's comments, Taiwan's government said China should respect the Taiwanese people's commitment to democracy
China should deal with cross-Taiwan Strait affairs pragmatically in a rational, equal and mutually respectful manner, Taiwan's China-policy-making Mainland Affairs Council said in a statement.
Most Taiwanese people have shown no interest in being ruled by autocratic China.
Taiwan President Tsai Ing-wen has repeatedly offered talks with China, which have been rebuffed as Beijing believes her to be a separatist.
Taiwan's government strongly disputes Beijing's sovereignty claims and says only the island's 23 million people can decide their future.