The bomb that exploded was left inside a trash can near a government office in a low-income neighborhood, TRT television said. Earlier, police used a controlled explosion to destroy a homemade device found near the Swissotel's perimeter walls.
There were no claims of responsibility and it was not known if the two incidents were connected.
Kurdish rebels, who are fighting for autonomy in southeast Turkey, have in the past launched attacks prior to their imprisoned leader Abdullah Ocalan's birthday on April 4. Militant leftist and Islamic groups are also active in the country.
On Sunday, officials from more than 70 countries met in Istanbul to discuss ways of ending the uprising in Syria, but the hotel would not say if any of the officials had stayed at Swissotel.
One of those officials, U.S. Secretary of State Hillary Clinton, left Turkey after Sunday's meeting.