This was the response:

Sir: I am directed to inform you that the address of the Central Council of your Association, which was duly transmitted through this Legation to the President of the United [States], has been received by him. So far as the sentiments expressed by it are personal, they are accepted by him with a sincere and anxious desire that he may be able to prove himself not unworthy of the confidence which has been recently extended to him by his fellow citizens and by so many of the friends of humanity and progress throughout the world. The Government of the United States has a clear consciousness that its policy neither is nor could be reactionary, but at the same time it adheres to the course which it adopted at the beginning, of abstaining everywhere from propagandism and unlawful intervention. It strives to do equal and exact justice to all states and to all men and it relies upon the beneficial results of that effort for support at home and for respect and good will throughout the world. Nations do not exist for themselves alone, but to promote the welfare and happiness of mankind by benevolent intercourse and example. It is in this relation that the United States regard their cause in the present conflict with slavery, maintaining insurgence as the cause of human nature, and they derive new encouragements to persevere from the testimony of the workingmen of Europe that the national attitude is favored with their enlightened approval and earnest sympathies. I have the honor to be, sir, your obedient servant,

~ Charles Francis Adams, US Ambassador