The attempted crossing came two weeks after more than 72,000 migrants surged into Ceuta, sparking tensions within the European Union and fuelling anti-immigration rhetoric among far-right parties worldwide.
At least 96 people died in the attempt to reach European soil.
A source in Morocco's Interior Ministry told Reuters those detained included 109 migrants from sub-Saharan Africa and two Moroccan citizens arrested in or around Fnideq, the Moroccan city opposite Ceuta.
According to Spanish news agency EFE, Moroccan police used tear gas to disperse groups of migrants gathered on hills about 3km from the border.
Reuters later saw hundreds of police officers, some in riot gear and others in plain clothes, returning from the hills outside Fnideq.
EFE and Spanish state broadcaster TVE said Morocco's Interior Ministry ordered their journalists to leave Fnideq immediately, without providing an explanation.
In Ceuta, Spanish soldiers guarded supermarkets while police heavily patrolled the enclave's main streets.
The city was calmer than in the days after the deadly crossing attempt on July 30.
Madrid has since installed a maritime barrier and deployed more than 500 additional police from mainland Spain, raising the total in Ceuta to more than 1600.
The Interior Ministry said the reinforcements would remain for as long as needed.
"We'll continue to deploy whatever personnel are necessary to restore normality as soon as possible and prevent events like those of July 30 from happening again," Interior Minister Fernando Grande-Marlaska said on Thursday.
About 5000 migrants remained in Ceuta, the minister said.
Reuters saw hundreds sheltering from scorching heat under makeshift bamboo shelters on the urban beach of El Trampolin.
Grande-Marlaska said migrants who entered irregularly would not be allowed to stay in the enclave, travel to mainland Spain or obtain legal status, except in rare cases involving extreme vulnerability. Those without a right to remain would be returned to Morocco, he said.
Earlier this week, Rabat said it was monitoring "the circulation of social media posts and messages of unknown origin" calling for a mass crossing on August 15, warning it would prosecute organisers and participants.
Driss Sadik, a 22-year-old from Fez who said he swam for five hours to reach Ceuta, urged others not to follow his example.
"The important thing I would advise people trying to cross: Don't cross now, my brothers. You're only going to suffer," he told Reuters.
