China has accused Taiwan's President Chen Shui-bian of using a planned referendum as "one-sided provocation".
China said Chen was ignoring "the Taiwan people's fundamental interests"
The poll's aim was to "realise Taiwan independence in the future," China's Taiwan Affairs Office was quoted by the official Xinhua news agency as saying.
On Friday, Mr Chen said the poll would ask voters if the island should beef up its defences if China refused to redeploy its missiles aimed at Taiwan.
China has threatened the use of force if Taiwan declares its independence.
The government in Beijing considers Taiwan a renegade province since the two sides split in 1949.
The United States has urged both sides not to make any unilateral moves to change the status quo.
"This is a one-sided provocation to the peace and stability of the Taiwan Strait," China's Taiwan Affairs Office said.
"We are resolutely opposed to this move on the separatist road to 'Taiwan independence'," the office's spokesman was quoted as saying by Xinhua.
The spokesman added that Mr Chen "has disregarded the immediate interests of the Taiwan people and the universal opposition of the international community".
On Friday, Mr Chen outlined plans for the referendum he wants to hold on 20 March alongside presidential elections.
Besides the missile issue, voters would also be asked if they back opening negotiations with China.