"Based on Justin's false statements at his news conference, and the fact that Canada is charging massive Tariffs to our U.S. farmers, workers and companies, I have instructed our U.S. Reps not to endorse the Communique as we look at Tariffs on automobiles flooding the U.S. Market!"
Merkel, widely seen as Europe's most prominent proponent of a generous refugee policy, has firmly rejected a plan put forward by Seehofer to turn back at German borders any asylum seeker already registered in another European Union country.
Kurz, who heads a right-wing government and whose country is taking over the EU's rotating presidency next month, appeared to back Seehofer's tough stance however when he said Austria's goal was to "halt the flow of illegal immigration".
Saxony's state premier, Michael Kretschmer, told Die Welt daily: "Of course, people who have no chance of getting asylum in Germany must be rejected at the border", adding that this includes people who had applied for asylum in other countries.
"Italy is going further than other states: migrants will not be accepted in the ports any more".
The interior ministry said in a statement that the unveiling of the plan had been pushed back because "several points still need to be agreed".
Touching the thorny issue of Germany's relatively low defence spending, Merkel acknowledged that Trump's criticism was partly correct and that Berlin had to do more to reach NATO's goal of spending to 2 percent of economic output on defence.
They told conservative lawmakers Tuesday they would try to negotiate a solution "in the coming days", participants who attended the meeting told AFP.
Seehofer, a former leader of the Bavarian Christian Social Union (CSU) which is facing a hard regional election in October, wants to show he is toughening up the rules in his 63-point master plan.
German Chancellor Angela Merkel found the contentious Group of Seven summit with U.S. President Donald Trump a "sobering" and "depressing" experience but said European leaders won't be "taken advantage of" on trade.
The CSU's secretary general Markus Blume said Germans wanted to see the government get immigration under control. We are sticking to them and whoever reneges on them is showing incoherence and inconsistency.
Merkel's March 2017 visit to the White House was marked by Trump either not hearing or ignoring her offer to shake hands in the Oval Office.
Despite the number of migrants effectively reaching the European Union through Albania is low, it has been surging in the last months.