To be honest smoking can actually help rid acne in some cases. But only IN SOME CASES! Do not let this be a reason to start smoking as believe me it is very hard to quit when you get older and realise you actually are slowly killing yourself!! If you have recently started smoking and have found that you have developed acne it could be a result of imbalanced hormones due to some of the side effects of smoking (like eating less, eating more, cravings for certain foods etc) it could also just be a coincidence as you are only 14 which is a common age to start getting acne. My advice: Stop smoking if you are, don't start if you don't, and get some face-wash to help wash oils off your face that cause acne.
This information may answer your question, but in my own words, I would recommend you try to find some help to quit smoking: http://funadvice.com/r/bqflaghmhc5
Its never given me acne, but maybe its different for other people