The challenges facing mayor Eduardo Paes were underscored by a wave of violence over the weekend which left 14 people dead.
Paes said Monday that Rio has "never hidden our problems."
He told the Global Sports Industry Summit: "We still have a long way to go and what happened this weekend showed that."
A firefight between rival gangs Saturday in a city slum killed at least 12 people and saw a police helicopter shot down. Two suspected drug traffickers were killed in another slum.
Paes said: "We are facing these problems, we are being tough with these problems."
Rio was awarded the games earlier this month.