"We will continue to treat foreign workers fairly, but we expect them to obey our laws and social norms," Lee said in his New Year message.
"The riot in Little India was inexcusable. We have taken firm action against the culprits. Several have been charged, others warned and repatriated, and still others advised to abide strictly by our laws," he said.
"The Committee of Inquiry (COI) will establish how the riot happened, and how we can prevent such incidents in future. The riot reminds us that we can never take good order, peace and stability for granted," Lee said.
The committee was set up after the December 8 riots, the worst outbreak of violence in over 40 years in Singapore.
During his speech, Lee also underlined the importance of foreign workers to Singapore.
"We are taking a balanced approach, reducing but not cutting off the inflow of foreign workers. This is why (Singapore) companies are finding it harder to hire the workers they need, especially SMEs (the small and medium enterprises),” Lee said.
"We are helping companies adapt by exploiting technology and becoming more productive. At the same time, we are encouraging firms to develop their Singaporean workforce and adopt fair employment practises. But we still need foreign workers to keep our economy running and to build critical infrastructure for Singaporeans," Lee added.
Around 400 South Asian migrant workers were involved in the rampage after the death of an Indian worker in a road accident on December 8 in Little India, a precinct of Indian-origin businesses, eateries and pubs where most South Asian workers take their Sunday break.
25 Indians are facing court charges for rioting and 56 Indians and one Bangladeshi were deported. The Singapore government has also issued police warning to 200 other South Asian workers.
Lee also said Singapore economy grew by 3.7 percent last year and he expects an economic growth of between 2 percent and 4 percent this year.