"Fifteen detainees are in custody, three of them had been extradited by Libya," he told the Moroccan Assabah newspaper.
"Indeed, these people were arrested as they prepared terrorist attacks," he added, declining to give details because of what he called the secrecy of the ongoing investigation.
Bouzouba gave no details on the three Moroccans arrested in Libya before their extradition to Rabat.
"Indeed, security services had arrested 100 suspects since March and 15 others in the latest days," Bouzouba added in an interview to L'Economiste newspaper, also printed on Friday.
He did not elaborate, citing the secrecy of the yet to be completed investigation.
Police sources said dozens of "radical Islamists" had fled a police crackdown in Morocco in the 1980s and 1990s to settle in Libya.
Last week, Morocco raised the security alert level to the highest rating of "maximum", suggesting an attack was imminent.
Morocco's Interior Ministry said it obtained intelligence information on the threat in recent days but gave no details.
Alert
The region has been on alert since al Qaeda's affiliate in North Africa, the Al Qaeda Organisation in the Islamic Maghreb which is based in Algeria, threatened to escalate its war against "corrupt" governments in the region and their Western allies.
The al Qaeda affiliate claimed responsibility for attacks in Algeria in the latest four months, including three in Algiers on April 11 when 33 people were killed and another on Wednesday that killed eight soldiers at an army barracks in Lakhdaria, 120 km, east of the capital.
On April 14, two suicide bombers detonated explosive belts outside US diplomatic facilities on Casablanca, killing only themselves.
The Rabat government at the time dismissed local media speculation of a link between attacks in Algiers and the death of the suicide bombers in Casablanca.
Five other suicide bombers blew themselves also in Casablanca in April and March, killing only themselves and a police officer.