The suspect was not carrying any explosives, according to initial reports, the private Dogan news agency said.
Police cordoned off the street outside the consulate after the detention of the suspect, who was described as "mentally instable," reports said.
Istanbul remains on high security alert after a female suicide bomber blew herself up in January in the Sultanahmet district -- the location of most of the biggest historic tourist attractions in the city, killing herself and a policeman.