Germany's Bild newspaper reported that raids earlier on Thursday were linked to a possible plan for Islamist militants to attack Alexanderplatz in central Berlin, a busy transport hub where the famous television tower is located.
Earlier, Berlin police said they had conducted raids in Germany in a search for four men suspected of having links to Islamic State (IS) militants and possibly preparing an attack in Germany.
State prosecutors in Berlin declined to comment on the Bild report which cited investigators.
Berlin police were not immediately available to comment.
Police arrested two men and one woman on existing warrants related to other matters.
The raids, carried out in part by special forces, took place on four flats and two offices in Berlin and also in properties in North Rhine-Westphalia and Lower Saxony. Police seized computers, mobile telephones and sketches.
One of the suspects is wanted by Algerian authorities, who believe he is a member of Islamic State, said the Berlin police.
Fears about an attack on German soil have risen since deadly bombings and shootings in Paris in November.