No, they would not do anything to stop Lincoln's war. Although they did point out as did the leaders of Great Britain, who jumped all over Lincoln's declared Blockade, that by formally declaring an international blockade against the South made it a war and not a simple rebellion that would have to be fought under the rules of the Laws of Nations AND forced the recognition of the Confederacy as a legal belligerent, protected by those rules.

Lincoln's blockade in itself was a declaration of war against a sovereign power.