Press secretary Sarah Huckabee Sanders said the president is too busy between now and the Dec. 12 special election to travel to Alabama.
President Donald Trump used the term Monday to refer to Sen. Elizabeth Warren, D-Mass., during a White House event for Native American veterans.
The White House briefing came amid feverish last minute negotiations on a Senate tax reform bill.
The Kentucky Republican urges his Senate colleagues to back the sweeping tax cuts.
Conway attacked Alabama Democratic Senate candidate Doug Jones during a recent television interview.
Conyers said he "expressly and vehemently denied the allegations made against me."
The White House briefing followed President Donald Trump's announcement that North Korea would be designated a State Sponsor of Terrorism.
Further investigation into allegations against Trump are not warranted, said the White House, because "people spoke very loud and clear" by electing him.