China has said that President Xi Jinping will meet with Prime Minister Modi at Friday's G20 Summit in Hamburg at an informal leaders' meeting of the BRICS countries on the sidelines.
Mr Trump will hold separate meetings with various leaders in Hamburg, including host Angela Merkel, and a potentially hard first meeting with Russian President Vladimir Putin.
German Chancellor Angela Merkel says Berlin can no longer rely on the U.S. when it comes to the United Nations, the Middle East, or European security.
Speaking to the German parliament last week, she said that "anyone who believes they can solve the problems of this world with isolationism and protectionism is making a big mistake".
Thousands of people have taken to the streets of the German city of Hamburg to protest against a Group of 20 (G20) summit that takes place next weekend. This will be the first official meeting between the USA and Putin since Barack Obama met with Putin two years ago.
On Monday, presenting her party's election platform, Merkel predicted "a whole series of thorny issues" at the G20.
"It is a great pleasure for us to welcome you here today at a time of turmoil in the world, when China and Germany can make a contribution to calming down this turmoil somewhat", Merkel said.
In total, the organizers expect several days more than 100 000 demonstrators.
"That I won't do", she said.
Fabrizio Bensch ReutersGerman riot police confront protesters during the demonstrations during the G-20 summit in Hamburg Germany
"It's not only going to be about (economic) growth but rather sustainable growth", Merkel said.
German authorities are bracing for trouble in Hamburg as they are anxious that the protests could turn violent.
Before that, protest groups will hold demonstrations throughout the city.
After the G20 meeting, Mr Turnbull will head to France to meet with President Emmanuel Macron and formally open the new Australian Future Submarine office in Cherbourg.
The Interior Minister had said on Tuesday that the German authorities believe that about 8,000 demonstrators were prepared to use violence.
Mrs May invited Mr Trump on a state visit to the United Kingdom shortly after he took office, but speculation that it may have been put on hold was fuelled by its absence from last month's Queen's Speech.
About 20,000 police will be deployed to ensure the security of the summit.
Trump later announced he was pulling the USA out of a landmark agreement to combat climate change reached in 2015 in Paris.