Francis was speaking to 50,000 German altar servers who had come to Rome on a pilgrimage.
He said: "Maybe many young people waste too many hours on futile things.
"Our life is made up of time, and time is a gift from God, so it is important that it be used in good and fruitful actions."
The Holy Father urged the young people to take part in more productive activities and outlined several things which he felt were not a good use of time: "chatting on the Internet or with smartphones, watching TV soap operas, and [using] the products of technological progress, which should simplify and improve the quality of life, but distract attention away from what is really important."