Netanyahu adjourned the second day of a meeting on Iran Wednesday because of media leaks, The Jerusalem Post reported.
"Something grave happened shortly after the conclusion of the meeting yesterday [Tuesday]: leaks from the security Cabinet meeting," the prime minister said at the beginning of Wednesday's meeting.
The two days of security discussions are the focus of an annual meeting on Israel's intelligence assessments. Netanyahu had said his Cabinet members must be able to speak freely about classified subjects.
"This is a basic tool in managing the country's security. Yesterday, someone severely undermined the confidence that Israeli citizens give to this forum," Netanyahu said. "He violated the most basic rules regarding the conduct of security Cabinet discussions."
Netanyahu has had to deal with leaks to the media before, the Post said. In July 2010 he ordered lie-detector tests for senior officials after sensitive information was leaked to a journalist.