TAIPEI, Jan 1 (Reuters) - Taiwan President Tsai Ing-wen had a New Year message for China on Saturday: military conflict is not the answer, but Beijing responded with a stern warning that if Taiwan crossed any red line it would lead to "profound catastrophe".

China claims democratically governed Taiwan as its own territory and has increased military and diplomatic pressure in the past two years to assert its sovereignty claims.

"We must remind the Beijing authorities to not misjudge the situation and to prevent the internal expansion of 'military adventurism'," Tsai said on Saturday in her New Year's speech, broadcast live on Facebook.

Taiwan says it is an independent country and has repeatedly vowed to defend its freedom and democracy.

Chinese President Xi Jinping said in his New Year address on Friday that the complete unification of "the motherland" was an aspiration shared by people on both sides of the Taiwan Strait.

On Saturday, after Tsai's speech, Zhu Fenglian, spokesperson of the Taiwan Affairs Office in Beijing, said: "We are willing to strive for the prospect of peaceful reunification."

"But if 'Taiwan independence' separatist forces continue to provoke and coerce, or even cross any red line, we will have to take decisive measures."

The pursuit of independence will only throw Taiwan into a "deep chasm" and bring about "profound catastrophe", Zhu added.

In recent months, Beijing has sent repeated air missions over the Taiwan Strait. Taiwan has said it will not give in to threats.

"The military is definitely not an option for solving cross-strait disagreements. Military conflicts would impact economic stability," Tsai said.

To ease tension in the region, both Taipei and Beijing must "work hard to take care of people's livelihoods and calm the hearts of the people" in order to find peaceful solutions to problems together, she said.

Tsai also said Taiwan would continue to monitor the situation in Hong Kong, adding that interference in the recent legislative election and the arrests this week of senior staff at the pro-democracy media outlet Stand News "made people worry even more about human rights and freedom of speech in Hong Kong".

"We will hold fast to our sovereignty, uphold the values ??of freedom and democracy, defend territorial sovereignty and national security, and maintain peace and stability in the Indo-Pacific region," Tsai said.