German Chancellor Angela Merkel will take pains to appear she is extending an olive branch to Greece, but she has little room to negotiate after Greeks voted "no" on economic austerity, former Dallas Federal Reserve President Richard Fisher said Monday.

"Ultimately, people report to their own people, and [Merkel] has to be supported by the German parliament and the German people," Fisher told CNBC's "Squawk Box." "There is a limit of tolerance, and she knows what that limit is."