Police Commissioner Chris Tang on Friday spoke of the force's need to gather "popular support" after intense criticism of its handling of last year's social unrest.
Protesters repeatedly accused officers of brutality, claims police strongly denied.
Speaking at an annual ceremony to remember officers who lost their lives on duty, Tang said the force won't let its guard down even though calm has returned to the city.
He said officers had faced "protracted violent protests and managed to bring light at the end of the tunnel towards peace and order."
"We must prevent a resurgence of the violence," the police chief said.
"Since calmness has gradually returned to our community, it is just as important for us to gather popular support and continue to fight the epidemic with the public," Tang continued.
He also said that the police have always put the people of Hong Kong first.
After observing a two-minute silence, the commissioner and other officers laid wreaths at the Roll of Honour.