Baku is hosting the Eurovision Song Contest, an international competition overseen by the European Broadcasting Union.
Human Rights Watch said that police in Baku assaulted protesters who were demonstrating against the government of President Ilham Aliyev ahead of the competition.
Giorgi Gogia, a regional researcher for Human Rights Watch, said Azeri authorities were sending the wrong message to the international community.
"The Azerbaijani authorities have gone to great lengths to prepare and polish Baku ahead of Eurovision, but police roughing up peaceful protesters casts a very dark shadow on all the festivities," he said in a statement.
Human Rights Watch said it monitored Monday demonstrations in central Baku. Around 100 activists had gathered near a central metro station before being runoff by authorities.
"Police used force to disperse the protest, rounding up protesters and forcing them onto buses," the rights group said in a summary of the events.