Lawyers say over 800 people were arrested when human rights groups and Islamists held rallies to mark the United Nations Human Rights Day on Sunday.
The arrests were broken up in the worst violence by the security forces since King Mohammed VI came to the throne last year.
Many of the protesters were arrested hours after the king had given a televised address in which he called for international norms of human rights to be applied in his kindom.
King's promises
Thirty-five human rights activists have been charged with disturbing public order after they held a sit-in on Saturday which riot police in the capital, Rabat, broke up violently.
The activists, who include the head of the Moroccan Association for Human Rights, are demanding an investigation into past abuses.
Meanwhile nine relatives of the head of the outlawed Islamist group, Justice and Charity, have appeared in court.
They were among more than 700 supporters of the group arrested on Sunday during protests demanding its legalisation.
Most of them have now been released without charge.
But nine relatives of the group's founder, Sheikh Abdesslam Yassine, including his activist daughter Nadia, were freed pending trial.
The BBC correspondent in Rabat said scores of protesters there were beaten during the demonstration, before being herded onto buses and beaten again.
Climate of fear
Observers in Rabat say that following a brief respite, a climate of fear is now returning to the kingdom.
In recent weeks, foreign journalists have been expelled and newspapers banned, and once again in Morocco it seems that the security forces are increasingly dictating policy.
Our correspondent says that concern is growing at the widening gap between the talk of the politicians and the violent reality on the kingdom's streets.