The firm said profits were $4.7bn (£3.5bn) in the three months to the end of September, up 80% year-on-year.
Chief executive Mark Zuckerberg told investors the firm's investments in security would "impact" profitability.
US lawmakers are examining the possible use of the platform for Russian propaganda activities during the 2016 US presidential election.
"We're serious about preventing abuse on our platforms," Mr Zuckerberg said. "Protecting our community is more important than maximising our profits."
