Security forces also captured 10 men suspected of being linked to the Islamic State group in southern Turkey.
Anadolu Agency says security operations targeted three different Istanbul addresses based on information gathered by the Turkish anti-terrorism agency and German intelligence services. A Turkish national, an Iraqi and a Syrian were detained.
In the southern province of Gaziantep, 10 men were detained after being caught trying to enter the country illegally from Syria. One was wearing a suicide vest.
The arrests come after a suicide bomber in Istanbul killed four foreigners. Turkey has witnessed a series of deadly suicide bombings, some claimed by Kurdish militants and others blamed on IS.