To decrease the width of the nose, most patients go for an alar/ala reduction or most commonly know as a nasal base reduction.
Alar means resembling wings, so the alar of the nose are the curved lower parts of the nose attached to the cheeks that sort of spread out like wings.
This procedure can also make the nostrils themselves smaller or more narrow.
(photo below for reference.)
The main caveat I will warn you though is that plastic or cosmetic surgery involves a lot about proportions.
This means proportions of your features
in relations to one another.
When a person has a feature they are unhappy with, they tend to focus on that one feature and nothing else. However, it is important to consider everything together.
If you do an alar reduction,
be aware that when your nose becomes less wide, your face may appear wider.
In order to find the procedure that works for you and your features, I highly recommend discussing this with a board certified plastic surgeon who specializes in rhinoplasty. He or she will take all of your features into account to give you a more comprehensive recommendation.