One question: are you overweight by any margin? If so, then you might experience an apparent decrease in your nose size if you cut down to a lower bf%. The face also stores fat to some degree in the area surrounding your nose (this varies from individual to individual, though), and the fatter you are, the more water you will also hold in your facial tissues. This makes the problem even worse. Being fat and bloated in the face can make the nose appear wider than it really is, and more snout-like.
If you are within a normal weight range, then I'm afraid there is very little short of surgery you can do to reduce the visible size of your nose. The genetic shape and size of one's nose is impossible to alter in any other way (unless you want to resort to trickery such as using make up to shade your nose in the right places, and I'm pretty sure you would object to that, being a man and all).