The official MAP news agency said the three journalists were given jail sentences up to two years for publishing derogatory comments made by Muhammad al Abbadi, a senior member of the Adl wal Ihsane.
Abbadi was also sentenced to two years in prison, as was Mustapha Kachnenni, the editor of the independent weekly Al Hayat al Maghribia.
The other two journalists of the weekly were sentenced to 18 months each.
They all were found guilty of "lack of respect due to the king, undermining the monarchy and inciting through printed matters acts likely to undermine the country's stability."
Criticism of the King is a strong taboo in Morocco.
The Moroccan National Press Union has condemned the sentences.Two other Moroccan scribes are already in jail on similar charges.
One of them is Ali Lmrabet, editor of satirical newspapers, Demain and Doumane.
He was first sentenced to four years in jail, later reduced to three years.