Francis made the comments at his general audience after appealing for a resolution to a labor dispute at Sky Italia, where employees are facing job cuts and relocation as the satellite channel moves offices from Rome to Milan.
Francis called for a solution that respects the rights of all, "especially families."
Speaking off-the-cuff, he added: "Those who for economic reasons or to conclude unclear negotiations, close factories and business ventures and take away jobs, this person is committing a very grave sin."
The audience was marked by an emotional encounter at its start as a small group of Chinese pilgrims approached Francis on their knees and wept at his feet as he blessed them in St. Peter's Square. The pilgrims said they were from Tianjin and brought with them a statue of the Madonna.
Francis has been working to improve relations with Beijing, particularly over the thorny issue of bishop nominations.
China has an estimated 12 million Catholics, millions of whom are loyal to the pope and worship in independent congregations outside the control of the communist party's Chinese Catholic Patriotic Association.