Taiwanese presidents usually use visits to allied countries to make what are officially stopovers in the United States, Taiwan's most important international backer and arms supplier, which frequently anger Beijing.
On two occasions in the past two years China staged military drills around Taiwan after presidential or vice-presidential stopovers in the United States.
On those stopovers, Taiwanese presidents often meet friendly politicians and give speeches.
Reuters reported last week that Lai was planning to stop off in Hawaii and maybe the US territory of Guam while he was in the Pacific.
Asked repeatedly by reporters at a news conference on Friday for details on the stopovers, Deputy Taiwan Foreign Minister Tien Chung-kwang said they were in the planning stages and would be announced at an "appropriate time".
China would do all it could to stymie the trip - Lai's first abroad since being inaugurated in May - but Taiwan would not be deterred, he said.
"We won't dance to their tune. We will do what we have to do and what we plan."
Speaking in Beijing, Chinese foreign ministry spokesman Lin Jian did not directly address the prospect of Lai transiting the United States, but said the "one-China principle" was the general consensus of the international community.
Of the 12 countries which maintain formal diplomatic ties with Chinese-claimed Taiwan, three are in the Pacific - Palau, the Marshall Islands and Tuvalu - and Lai will go to all of them starting from November 30, his office said.
His official schedule has him then arriving in the Marshall Islands only in the following week, on December 3, without saying where he would be in the intervening period.
The Pacific island nations visits are also important as China is competing for influence with the United States there and has been gradually whittling away at the number of countries in the region who retain ties with Taiwan.
In January, tiny Nauru switched relations back to Beijing.
Palau, Marshall Islands and Tuvalu all put out statements on Friday saying they welcomed Lai's visit.
"As a long-term partner and good friend of the Marshall Islands, we look forward to the warmly receiving President Lai," the office of President Hilda Heine said on its Facebook page.
China has ramped up its military activities around Taiwan in the past five years, including holding another round of war games last month it said were a warning to "separatist acts".
Taiwan's government rejects Beijing's sovereignty claims and says it has a right to engage with other countries and for its leaders to make foreign trips.
