"It is likely we will have what is called a local outbreak," he told Chris Wallace on Fox News Sunday.
So far, there have been over 350 cases of people who have been infected abroad and returned home, but there have been no cases of infections occurring inside the United States.
"It would not be surprising at all — if not likely — that we're going to see a bit of that," he said. "We're talking about scores of cases, dozens of cases, at most."
He also spoke about the possibility of other types of neurological damage caused by the virus, which is transmitted by mosquito bites.
"There are only individual case reports of significant neurological damage to people, not just the fetuses, but an adult that would get infected. Things that they call meningoencephalitis, which is an inflammation of the brain and the covering around the brain, spinal cord damage due to what we call myelitis," he said. "So far they look unusual, but at least we've seen them and that's concerning."
Fauci used the airtime to make his case for some $1.9 billion in emergency funding so work can begin on developing a vaccine for the virus.
"We have to act now," he said. "I can't wait to start developing a vaccine."
Earlier this month, CDC Director Tom Frieden confirmed that the Zika virus causes birth defects.
Frieden added that the CDC would continue to study whether microcephaly in children born to mothers infected with Zika "is the tip of the iceberg of what we could see in damaging effects on the brain and other developmental problems."