Mr. Xi’s offer of dialogue appeared unlikely to win over Taiwanese wary of the idea that they could retain autonomy under China’s principle of “one country, two systems,” Yun Sun, a researcher on Chinese policy at the Stimson Center in Washington, said by email after the speech.

“Xi is correct in that differences in political systems are the root of the problem,” Ms. Sun said. “But ‘one country, two systems’ is unlikely to be the answer the Taiwanese people embrace.”

Mr. Xi’s speech was a sharp reminder that, even amid many other external disputes, Chinese leaders remain preoccupied with Taiwan, especially their concern that the island could defy their demands and embrace formal independence.

China is Taiwan’s biggest trade partner, taking over 30 percent of its exports. Many Taiwanese, though, bridle at Beijing using its growing influence to isolate them from international participation, and to press them toward eventually accepting Chinese sovereignty over the island.

Since coming to power in late 2012, Mr. Xi has warned Taiwan against any shift toward independence and repeatedly met with Taiwanese politicians from the Kuomintang, the party that ruled China before the Communist Party and that now favors closer ties with Beijing. But Mr. Xi’s address was his first major speech as president devoted to Taiwan, said Bonnie S. Glaser, an expert on Chinese foreign policy at the Center for Strategic and International Studies in Washington.

“My initial impression is that the speech is a reaffirmation of current policy,” Ms. Glaser said. She also noted that despite Mr. Xi’s renewed call for unification, he did not set a deadline. “It is notable that there is no mention of a timetable or deadline for reunification — it is just a goal,” she said.

Mr. Xi indicated that China’s multipronged pressure on Taiwan is likely to persist after Ms. Tsai’s Democratic Progressive Party, which is wary of moving closer to China, suffered stinging setbacks in local Taiwanese elections in November. The opposition Kuomintang won mayoralties in Taiwan’s three most populous cities, prompting Ms. Tsai to resign as leader of the Democratic Progressive Party, though she remains Taiwan’s president.