Security has been stepped up for the visit of Brack Obama following the terror attack in Manchester
The arrests were part of dawn raids by police in Berlin on Wednesday, ahead of a busy weekend in the German capital.
Police said the raids targeted a gang of armed drug smugglers and that nine arrests had been made, four of which were men from the "violent Islamist" scene.
None of the arrests were linked to the Manchester bombing which killed 22 people attending an Ariana Grande concert on Monday.
Security is nevertheless being stepped up in Berlin following the attack, as the city prepares to welcome an estimated 100,000 visitors in the coming days.
As well as the German football cup final between Eintracht and Dortmund at the Olympiastadion on Saturday, former US president Barack Obama is in town for a gathering of German Protestant Church members as the country marks the 500th anniversary of the Reformation.
Mr Obama is taking part in a podium discussion with German Chancellor Angela Merkel near the city's iconic Brandenburg Gate on Thursday.
Speaking during a radio interview, Berlin's interior affairs senator Andreas Geisel said: "We'll take another look, but our security plans are designed so we're well prepared for events like that in Manchester."
Memories are still fresh of the Berlin Christmas market attack last December, in which 12 people were killed, and flags hung at half-mast across Germany on Wednesday to express solidarity with Manchester after the attack.
Security has been beefed up for the visit of Barack Obama and Angela Merkel in Berlin
Thousands have turned up to see the former US president in conversation with the German chancellor
Mr Geisel said 6,000 police will be deployed on Berlin's streets over the Ascension Day long weekend, which begins with the German protestant church's biennial four-day Kirchentag festival.
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Interior minister Thomas de Maiziere told Bild newspaper: "We mustn't focus exclusively on access controls.
"The Manchester events have shown that the situation at the end of the event have to be looked at carefully, when people leave the hall or stadium."
The arrests in Berlin come after German intelligence officials revealed Manchester bomber Salman Adebi was in Dusseldorf, 350 miles from the German capital, four days before the attack.
Manchester bombing: Mourning for Manchester
Wed, May 24, 2017
Mourning for Manchester. Makeshift memorials and tributes to victims of the deadly attack at an Ariana Grande concert.
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Members of the public lay flowers and pay their respects in St Ann's Square, Manchester to the 22 killed at Mondays terror attack
Security agencies are investigating a possible terror network that may have assisted Adebi, 22.
So far eight people, including Adebi's father and brother, have been arrested by Greater Manchester Police in connection with the investigation.
Yesterday French interior minister Gerard Collomb claimed Adebi had travelled to Syria and had proven links with ISIS.