City police chief Comm Datuk Seri Mazlan Lazim said that the organisers failed to notify the police regarding the assembly.
"We controlled the situation then. But the organisers did not give notice of the assembly beforehand.
"We will call in the organiser for their statement," he said during a press conference on July 17 at the Bukit Jalil police station in southern Kuala Lumpur.
He added that the situation was under control and that no outward incidents occurred during the gathering.
Yesterday a planned protest by an Umno-linked group, dubbed Pemantau Malaysia Baru (New Malaysia Watchdogs), failed to take off outside Parliament building after the police intervened.
The group wanted to protest against alleged attempts by the Government to undermine the Yang di-Pertuan Agong's power, the position of Islam, and bumiputra rights in the country.
The group was led by Umno supreme council member Datuk Lokman Noor Adam.