Appearing on CNN's "State of the Union" Sunday, senior adviser Dan Pfeiffer said it is a "cardinal rule when you know a situations like these, not for just for this White House but for all White Houses ... you do not interfere in an independent investigation and you do not do anything to give off the appearance of interference in an independent investigation."
A Department of the Treasury inspector general's report found employees at an IRS field office in Cincinnati singled out for extra scrutiny some conservative political groups applying for tax-exempt status as non-partisan.
Pfeiffer said U.S. Rep. Darrell Issa, R-Calif., who knew about the inspector general's investigation, did not say anything publicly about it for the same reason.
"Because when you're dealing with a non-partisan entity like the IRS, you want to ... actually have an actual independent investigation before you make allegations," he said.
Pfeiffer said the IRS' activity was inexcusable but he would not comment on whether the head of the tax exempt division, Lois Lerner, should have informed Congress about the agency's alleged targeting of conservative groups.
"I think, in this case, I can't speak to the facts of what she knew or what she did. That's why we're going to have the acting commissioner to look at it," he said.
Notable deaths of 2014 [PHOTOS]