Taiwan's new president Tsai Ing-wen warned China that "suppression" would harm cross-strait ties Saturday after her landslide win against the ruling Beijing-friendly Kuomintang.

"Our democratic system, national identity and international space must be respected. Any forms of suppression will harm the stability of cross-strait relations," she told reporters at the Democratic Progressive Party's headquarters in Taipei.

It came on the day that outrage erupted over the treatment of 16-year-old Taiwanese K-pop star Chou Tzu-yu who was forced to record a video apology after angering Chinese netizens by flying a Taiwanese flag in a recent online broadcast.

Tsai specifically referred to Chou in her address, saying her case had "shaken Taiwanese society".

"This particular incident will serve as a constant reminder to me about the importance of our country's strength and unity to those outside our borders," she said.

Earlier in her speech, Tsai pledged to "work towards maintaining peace and stability" in China relations, but emphasised it must reflect public will.

"We must ensure that no provocations or accidents take place," she said.

Support for Tsai has surged as voters have become increasingly uneasy about a recent rapprochement with China under KMT president Ma Ying-jeou, who must step down after a maximum two terms.

As the economy stagnates, many are frustrated that trade pacts signed with the mainland have failed to benefit ordinary Taiwanese.

The DPP has a much more cautious approach to China, although Tsai has toned down its traditionally pro-independence message in campaigning.

Although Taiwan is self-ruling after it split with China following a civil war in 1949, it has never declared independence and Beijing still sees it as part of its territory awaiting reunification.