Dujarric was asked to comment on press reports quoting Turkish Foreign Minister Mevlut Cavusoglu as saying that Turkey had initially chosen to work with Saudi Arabia, but had now concluded that an international probe was needed.
"We saw the press reports that something may be coming," Dujarric said. "We have not received anything, and as we have said, the secretary-general would need a mandate from a UN legislative body to proceed with an international investigation."
The New York Times quoted unnamed Turkish officials as saying that Ankara was weighing requests for an investigation by the human rights commission of the Organization of Islamic Cooperation, as well as for an independent inquiry under the UN secretary-general.
Earlier on Thursday, the United States imposed sanctions on 17 Saudi nationals for human rights abuses related to their roles in the October 2 murder of Khashoggi at the Saudi Arabian Consulate in Istanbul on October 2.
Saudi Arabia eventually admitted that Khashoggi had been murdered and indicted 11 people this week, but the nation has not indicated who gave an order to kill the columnist. Saudi Crown Prince Mohammed bin Salman, the country's de facto ruler, has denied any involvement.