His comments are being seen as a response to recent attacks against foreign targets in Casablanca and the rise in support for Islamic groups in his country.
"Morocco will never accept that Islam is used as a springboard for the satisfaction of ambitions of rule in the name of religion," he said in a nationwide address on television and radio.
He said “Islamists” would not be allowed to carry out terrorist acts, accuse people of apostasy, or kill them.
Islamic party ban
Speaking on the occasion of a royal festival, he called for the speeding up of legislation banning the setting up of political parties on the basis of religion, race or language.
"There is no place for political parties that monopolise Islam," he said.
"There is no place for political parties that monopolise Islam" --King Mohammed VI
The king said he wanted to transcend the "cruel memory" of the May 16 "terrorist attacks" when five suicide bombers blew themselves up almost simultaneously at foreign and Jewish targets.
Besides the 44 dead, 100 people were injured in the atrocity.
Scores of suspects linked to the attacks and suspected of membership of a banned radical group Salafia Jihadia are currently on trial in Casablanca.
Analysts say the king may feel threatened by rising support for banned Islamic parties such as the Justice and Charity Movement, led by the popular Abdelsalaam Yassine.
Justice and Charity say the institution of monarchy is against the precepts of Islam and are seeking to establish an Islamic state.