"We're going in the opposite direction" from companies that are building their own phones, such as Google and Apple, he said. "We want to build a system that's as deeply integrated as possible into every device people use."
Zuckerberg has kept a low profile since the company's initial public offering in May, which was dogged with technical problems and has resulted in Facebook and the Nasdaq stock market facing at least 30 lawsuits from disgruntled investors and others.
Some of the lawsuits accuse Facebook of unfairly sharing information about its business with its underwriters ahead of the IPO, putting the wider investment community at a disadvantage. Other lawsuits target the Nasdaq, on which Facebook's shares are traded, for technical problems on the day of the IPO.
In addition, Facebook's stock price has declined by about half since the offering, in part over concerns that the company can't sell ads effectively to the millions who access its service from mobile devices.
Facebook's shares closed at US$19.43 Tuesday, up slightly from the previous day but down from its initial offer price of $42.
Asked if the stock price has caused a morale problem at Facebook, Zuckerberg deadpanned: "It doesn't help."
But Facebook employees are used to the ups and downs and are motivated by building great products, he said.
"Facebook has not been an uncontroversial company in the past; it's not like this is the first up and down we've had," he said.