The Catechism of the Catholic Church says:
2290 The virtue of temperance disposes us to avoid every kind of excess: the abuse of food, alcohol, tobacco, or medicine. Those incur grave guilt who, by drunkenness or a love of speed, endanger their own and others’ safety on the road, at sea, or in the air. (1809)
Catholic Church. (1997). Catechism of the Catholic Church (2nd Ed., p. 552). Vatican City: Libreria Editrice Vaticana.
This would imply the acceptability of moderation in tobacco use. At the same time:
Respect for health
2288 Life and physical health are precious gifts entrusted to us by God. We must take reasonable care of them, taking into account the needs of others and the common good. (1503; 1509)
Cigarettes deliver nicotine which has been shown to be quite addictive. Cigarettes don't have a medical benefit and in fact have proven to be quite harmful. While there is no explicit statement that they are immoral, it would seem that they are not only not beneficial but harmful and should probably be avoided.