China is in denial about its alienation of Taiwan and needs to rethink its approach to the island, the top official in charge of managing Taipei's relationship with Beijing said on Friday.

"Somehow they need to think of how to do some soul-searching," said Andrew Hsia, the head of Taiwan's Mainland Affairs Council. He said that his counterparts in Beijing seemed "puzzled" by growing antipathy among Taiwanese people toward China.

The comments from Mr. Hsia, delivered in a conversation with The Wall Street Journal in New York, show how mainland China's declining image in Taiwan has complicated relations ahead of the island's presidential elections, whose outcome could frustrate Beijing's desire for closer ties.

Relations between Taiwan and China have long been fraught; the two sides split in 1949 following a civil war. The past seven years, Taiwanese President Ma Ying-jeou and his ruling Nationalist Party have worked to reduce tensions in a bid to boost the island's economy. But stagnating wages and growing income inequality have become front-burner issues for many in Taiwan, and some see trade and commercial dealings the mainland as contributing to those problems. They question the concessions Taipei is making to Beijing, which has refused to disavow force in bringing about eventual reunification.

Student protesters opposed to a trade pact with Beijing took over Taiwan's main legislative chamber last year. The Nationalist Party--also known as the Kuomintang--took a beating in local elections in December, in part because of disillusionment with its China policy.

A poll conducted by National Chengchi University shortly after the elections showed 23% of Taiwanese people supported independence for the island, the highest level since polling began in 1992. The number of people identifying themselves solely as Taiwanese, as opposed to Chinese, also set at new high at 60.6%.

Despite that, Mr. Hsia said, Beijing has continued to act in ways that irritate people and officials in Taiwan. He cited provisions in China's new National Security Law requiring Taiwanese people to protect the country's sovereignty, which he described as "not acceptable," and entry permit cards Beijing began issuing to Taiwan residents without consulting or notifying the Taiwanese government.

He also mentioned Taiwanese violinist Tseng Yu-chien, who was identified by organizers as being from "Taipei, China" rather than Taiwan after he won the silver medal at the International Tchaikovsky Competition in Russia earlier this month.

"We were told this was because of pressure coming from the [Chinese] embassy," Mr. Hsia said. "I can give you example after example."

The Chinese Embassy in Washington D.C. and the Chinese consulate in New York City didn't immediately respond to requests for comment.

Mr. Hsia said Chinese officials were confused when he mentioned the increasingly negative perceptions of China in Taiwan to his counterpart, Chinese Minister of Taiwan Affairs Zhang Zhijun, during a meeting in May.

"Since then, we got word that they were not happy with the description, but this is the truth, this is the reality," he said.

The KMT is expected on Sunday to confirm Hung Hsiu-chu, an outspoken former teacher, as its candidate to take on Tsai Ying-wen of the Democratic Progressive Party in presidential elections next fall. Ms. Tsai, who is widely favored to win in polls, has said she favors maintaining the "status quo" with China. It's a position shared by most Taiwanese, according to government polls.

The Taiwan-China relationship is better than it has been throughout most of its history, Mr. Hsia said. But, borrowing a page from Beijing's own diplomatic phrase book, he said it needs to be "much more sensitive to the feelings of the Taiwanese people."

Political strife in Hong Kong had made matters worse, he said. Last month, legislators there voted down a Beijing-backed proposal that would have allowed residents in the Chinese territory to directly elect the city's top official but only from a list of preapproved candidates. The proposal had earlier sparked massive street protests that were closely followed in Taiwan.

"If you truly wanted to win the hearts and minds of the Taiwanese people, make a good example in Hong Kong. Obviously it's not helping," he said.

--Josh Chin