Nowadays there is much condemnation of how European colonial powers took the New World by force from the indigenous people who lived here before. Were there any significant groups or individuals in Europe expressing such condemnation at the time, saying "we have no right to take this land"? If so, how much influence did they wield? How early did such condemnation emerge? Why did they ultimately fail?
This might not be exactly what you're looking for, but in the Royal Proclamation of 1763 King George III himself implemented a piece of legislation that made it illegal to settle west of the Appalachian mountains (basically anywhere west of the 13 colonies). This was done to organize and solidify Britains claim on the original colonies, as well as affirm political relations with various Native American tribes at the time. This obviously failed due to the ensuing revolution, and is in fact one of the primary reasons as to why many Native American tribes at the time fought alongside the British (or at least supported them somehow). Some revolutionaries thought that settling throughout the continent should be their right, and then fought to claim it. This eventually resulted in the "manifest destiny" in which thousands of natives were both killed and displaced