The so-called “Gefahrengebiet” gives officers extra powers to stop, search and ban people from the area and covers the red light district of the Reeperbahn, the Old Town, St Pauli and Altona Nord.
Police said they would only stop those acting suspiciously or people known to them, but one man told the Hamburger Morgenpost newspaper he was stopped three times in 30 minutes while out for a walk.
It is the largest area ever made into a restricted zone by the city’s authorities.
Police said in a statement on Sunday they had stopped 263 people since the zone was introduced on Saturday at 6am. They said it was necessary after attacks on officers on December 12th, 20th and 28th.
It also follows protests in Hamburg on December 21st which turned violent.
Of the 263 people stopped, 62 were banned from the area. Two restraining orders were issued and one person was taken into custody after they pulled barriers down and put a mask over their face.
Three people were also charged on suspicion of violating the Explosives Act. The officers found pyrotechnics, tools and masks.
The city’s famous Reeperbahn lies in the heart of the zone, but police said the measures were “not intended to excessively burden residents or visitors to the entertainment district.”
They added: “We want to make it very clear with this measure that Hamburg police will exhaust all legal options to protect life and limb of its officers.”
“The measures will be continued until further notice,” the statement added.