Washington (CNN) President Donald Trump says he's not considering firing special counsel Robert Mueller, but added that his "people" are "very upset" about the counsel's decision to obtain tens of thousands of emails from the Trump transition team.

Asked Sunday night if he was considering firing Mueller, Trump said, "No, I'm not."

Following his return to the White House from Camp David, Trump told reporters that he thought it was "pretty sad" that the special counsel got a hold of the emails, which Trump transition lawyers said Mueller's team " unlawfully " obtained. The President also reiterated that there was no collusion between Russian and his campaign.

"I can't imagine there's anything on (the emails), frankly, because as we said, there's no collusion. No collusion whatsoever," Trump said. "But a lot of lawyers thought that was pretty sad."

Lawyers representing the Trump transition wrote to members of Congress accusing Mueller's team of obtaining unauthorized access to tens of thousands of transition emails in the course of its Russia investigation, including what they claim to be documents protected by attorney-client privilege.

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