(CNN) Rudy Giuliani, President Donald Trump's lawyer, said the line special counsel Robert Mueller wrote in his report about not exonerating Trump on obstruction of justice is a "cheap shot."

"This is a cheap shot," Giuliani told CNN's Chris Cuomo on "Cuomo Prime Time," adding, "This is unprofessional."

Mueller's investigation of whether the President committed obstruction of justice did not conclude that Trump had committed a crime but it also "does not exonerate him," Attorney General William Barr quoted from Mueller in his summary to Congress of the special counsel's report.

"They don't have to exonerate him, you gotta prove he's guilty," Giuliani said. "Even for impeachment," he added.

After a nearly two-year investigation, Mueller did not find Trump's campaign or associates conspired with Russia, Barr said Sunday. Giuliani argued that Barr, in effect, exonerated Trump in the rest of the letter released Sunday.

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