The reporters were released after being taken to a police station in the capital, Baku.
The journalists, most of them women, chanted slogans including "Khadija, we are with you!"
Ismayilova's reports have implicated President Ilham Aliyev, who will run for a third term in October, and his family in improper financial activities worth hundreds of millions of dollars.
Ismayilova, who reports for the Azerbaijani Service of the U.S.-funded broadcaster, responded defiantly to the appearance on the Internet in early 2012 of an explicit video in which she was shown.
On August 1, RFE/RL called on Azerbaijani authorities to investigate the new video, which contains intimate and illegally obtained images of Ismayilova.