Greenberg noted that the TARP banks were forced to take the money regardless of need because the government wanted to create a level playing field in terms of public perception.
"It's unfair, it's unwarranted, it's unprecedented," Greenberg said regarding the bank tax. "Is it constitutional? I don't know, I guess so."
And he cast doubt on plans to reinstitute a form of the Glass-Steagall Act that was repealed in 1999. Some consider the rollback of the law that allowed the combining of retail and investment banks as pivotal to the financial crisis that unfolded at the end of the last decade.
"That was repealed and I don't think they can do anything about that," Greenberg said. "The egg has been scrambled and I don't think they can put it back in the shell."
He also rejected sentiment from the public and in Washington that there should be pay limits on top executives at well-run institutions such as Goldman Sachs .
"They don't recognize that in finance there are superstars and superstars should get paid regardless of what industry it is," he said.
"People just don't understand—they want these institutions to have limits on how much they can pay people and they don't realize these huge organizations need top talent," Greenberg added. "You don't win the World Series and not have A-Rod" he said, referring to New York Yankees third baseman Alex Rodriguez.