* Twitter messages can destroy trust in seconds-German minister
* France, Germany stand by G7 communique
Having left the G7 summit in Canada early, Trump's announcement on Twitter that he was backing out of the joint communique torpedoed what appeared to be a fragile consensus on a trade dispute between Washington and its top allies.
Trump also took aim at Canadian Prime Minister Justin Trudeau and said he might double down on import tariffs by hitting the sensitive auto industry, throwing the G7's efforts to show a united front into disarray.
G7 members Germany and France said they stood by the communique despite Trump's decision.
"In a matter of seconds, you can destroy trust with 280 Twitter characters," German Foreign Minister Heiko Maas said when asked about Trump's U-turn, adding it would take much longer to rebuild lost trust.
Trump's conduct was "actually not a real surprise, we have seen this with the climate agreement or the Iran deal," Maas, a senior member of the Social Democrats, a partner in Chancellor Angela Merkel’s governing coalition, told reporters in Berlin.
France and Europe are standing by the G7 communique, a French presidency official said, adding anyone departing from the commitments made at the summit would be showing their "incoherence and inconsistency".
"International cooperation cannot depend on being angry and on sound bites. Let's be serious," the French official, speaking on condition of anonymity, told Reuters.
Trump has infuriated the European Union, Canada and Mexico by imposing tariffs on steel and aluminium imports.
Trump and European allies are also at odds over Trump's decision to withdraw the United States from the Iran nuclear deal and the Paris agreement to combat global warming.
"We have to keep a cool head now and draw the right conclusions," Maas said.
Europe's answer must be to stick even closer together, defend its interests and strengthen alliances with countries such as Japan and Canada, he said.
"Europe united is the answer to America First," Maas said in a tweet.
A German government spokesman said that Berlin continues to support the G7 communique despite Trump's decision.
"Germany stands by the jointly agreed communique," spokesman Steffen Seibert said in a statement.
The top White House economic adviser accused Canada's prime minister on Sunday of betraying Trump with "polarising" statements on US trade policy that risked undermining the American leader on the eve of a historic summit with North Korea.
Larry Kudlow, director of the National Economic Council, lashed out at Trudeau as "amateurish" and "sophomoric" for a news conference he gave after Trump left the G7 summit on Saturday.
In his press conference, Trudeau had spoken of retaliatory measures that Canada would take next month in response to Trump's decision to slap tariffs on steel and aluminum imports.