I don't agree with a lot of what Trump says, but I don't hold him accountable for others' actions unless he specifically called for violence which I don't think he did in this case. He does say some questionable things, but has always disavowed violence on both sides.
Obama has promulgated lots of anti-police rhetoric, and there are some who would blame him for certain attacks on police. I disagree with things he said, but would not blame him for any of that.