If there were any laws for annexing territories. Did the natives offer any sort of resistance?
Yes. And yes, the Hawaiians did resist the change.
The American presidents of the 1880s and early 1890s flexed some of their early foreign policy muscle by negotiating treaties to bring Hawaii into our sphere of national influence. Trade rights, a military base at Pearl Harbor, that sort of thing.
Then in 1893 a small cadre of Hawiian-American businessmen (who were also members of the Hawiian government) staged a coup against Queen Lili'uokulani. They took control of the country and went ahead with the plan, asking the US to annex them. This was probably the biggest act that many Hawaiians opposed.
But the American President was Grover Cleveland, an ideological isolationist. He refused to go forward. So the businessmen awkwardly went about setting up the Republic of Hawaii. Some Hawaiians would rebel to try to restore the queen, but the Republic put them down.
Several years later during the Spanish American war an imperialist mood swept Washington. Now both President and Congress favored annexation. The Hawiian Republic was still willing, and the annexation happened.
For more info a good book that covers the mood and thought of the time, the annexation, and the whole period is Fareed Zakaria 's From Wealth To Power.