Bono fears the G8 nations offer too little help or may wriggle out of existing promises.
The "Raise Your Voice Against Poverty" concert will be held 7 June in Rostock, near Heiligendamm.
In addition, another celebrity campaigner Bob Geldof is urging G8 leaders to hold onto pledges they have made at the Gleneagles summit chaired by Tony Blair almost two years ago.
"There is a great crisis of credibility," says Geldof, "If I sign a contract in my business life and don't fulfil it, I would be sued. I could go to jail. Do these leaders live outside the norms of human behaviour?" he asked.
Heads of State and government of Germany, France, Great Britain, Italy, US, Canada, Japan, and Russia are currently attending the G8 summit in Germany, which takes place June 6 to 8.
Last Saturday, 10,000 people joined 'The World Can't Wait' rally at the River Thames in London, calling on G8 leaders to take decisive action against poverty and climate catastrophe.