Hamburg police skirmished with protesters ahead of this week's Group of 20 summit, days before world leaders gather for the meeting hosted by Chancellor Angela Merkel.
The highly anticipated meeting with [sic] also be the first time Trump comes face to face with the Russian leader since his election.
It pledges support for North Atlantic Treaty Organisation but says that Europe has to take greater responsibility for its own defense.
Thousands have attended a rally in the northern German city of Hamburg to protest at an imminent meeting of leaders of the world's major industrialized and emerging economies, known as G20. It scraps the 2013 pledge to strengthen economic ties with the US, and pledges to "reinvigorate the relationship with France", whose new president, Emmanuel Macron, has been critical of Trump.
Ms Merkel - who no longer considers the United States a friend based on her political party's campaign material - is set to meet with Mr Trump later this week at a summit in Germany with 20 global leaders.
The Interior Minister had said on Tuesday that the German authorities believe that about 8,000 demonstrators were prepared to use violence.
Authorities say roughly 8,000 of those are prepared to use violence
"While we seek chances to cooperate for everyone's benefit, globalization is seen in the American administration as a process which isn't about win-win situations, but about winners and losers", she said.
In addition to the no-protest zone, tightly secured transit corridors were set up to ensure that convoys will be able to keep moving so they don't become targets for violent demonstrators or extremist attacks.
In his talk with Gentiloni, the US leader again voiced his appreciation of the Italian official's efforts in hosting a successful Group of Seven meeting in May, the White House said.
"The United States made some of the worst Trade Deals in world history", Trump tweeted. Critics of Mr Trump's decision on the climate agreement have said that the USA is forsaking its role as a global leader on one of the most important issues affecting the planet. "It's a criminal act to set vehicle tyres on fire or injure police officers", he told a group of newspapers.
The 11,000-square-metre centre in Hamburg's southern Harburg district has 70 group cells and 50 single cells that can hold as many as 400 detainees, according to police spokesman Timo Zill.
Arsenal edge nearer to Alexandre Lacazette deal?
Speaking on Tuesday evening, Aulas told Canal Plus that the 26-year-old is likely to stay with the club for a ninth season. In an interview with the French broadcaster, Aulas said: "I do not think that Alexandre Lacazette will leave this summer".