The four men charged Thursday will be in remand till Dec 19, when the case will next come up for hearing, to facilitate further investigations, the Straits Times reported Thursday.
Sellamuthu Elangovan, 45, Ammasi Venkatesan, 27, Selarasu Dhanapal, 25, and Arumugam Karthik, 24, are accused of throwing pieces of hardened concrete at police officers, among other charges, following the death of an Indian worker in the Little India neighbourhood Dec 8.
Earlier, 27 Indian nationals were charged in connection with the case.
The riots, involving some 400 South Asian workers, broke out after an Indian worker, Sakthivel Kumaravelu, was killed after being run over by a bus in the Little India ethnic neighbourhood, known for its Tamil cultural elements and aspects of other Indian cultures.
The driver involved in Sunday night's accident was charged Dec 10 with causing death by negligence.
Mobs attacked officers who responded to the accident, but police said they did not fire a single shot while trying to bring the situation under control.
It was the biggest riot in Singapore in some 40 years. Around 22 police officers who sustained injuries have been discharged after treatment in hospital.
Singapore Prime Minister Lee Hsien Loong offered his deepest condolences to the family of Sakthivel Kumaravelu, the accident victim, and urged people to remain calm and continue with their daily lives.
The prime minister has also ordered that a probe committee be set up to investigate the incident.