When exactly did the confederate authorities make this clear to him? Lincoln was told by a lot of people that his actions would lead to war. Hurlburt gave his opinion, Lamon gave his, other people added their impressions as well. But if any person in power in the Davis government threatened it then I'm not aware of it. Lincoln was no doubt acting on the hope that cooler heads would prevail, not knowing that there were no cool heads down there. Might Lincoln also have been resigned to the fact that absent a complete surrender to all their demands, the South would start a war regardless of what he did? Maybe. We will never know for sure.
Did Lincoln know that if he sailed into the harbor, the fighting would begin... yes or no?
But please stop insulting Lincoln's intelligence.