Every single country in the Americas has exterminated its native population (including Canada and the United States), and Argentina is not an exception. In some of the countries (Brazil, Peru.etc), the few remaining natives are still getting exterminated (although with no direct government support).
On the other hand, countries such as Bolivia, Venezuela, and Argentina deserves credit for showing the courage to apologize for the mistakes in the past. Venezuela has banned the American terrorist organization New Tribes Mission (which exterminated a large number of Amazonian tribes in the 1980s and 1990s). Bolivia has recognized the Native American Religion, and has given it equal status along with Catholicism (despite the pope going ballistic when he heard the news).
Argentina is perhaps the boldest country in the Americas, in recognizing the genocide against the native population. The main perpetrator (Julio Argentino Roca) of the 1879 genocide was stripped of all his honors, and the government apologized for the extermination of the Tehuelche. This was done despite the blatant threats from the powerful catholic lobby.