Grisham suffered bruises when a scuffle broke out Sunday between North Korean security guards and members of the media trying to get close to President Trump and North Korean leader Kim Jong Un as they met at the Demilitarized Zone, the Associated Press reported.
The new press secretary was reportedly pushing back against the guards, trying to help members of the White House press corps position themselves to cover the historic moment between Trump and Kim.
Several reporters tweeted about the clash between the guards and the media.
It was not immediately clear if Grisham required medical attention or if anyone else was injured or detained by the guards.
Grisham, 42, had been a spokeswoman for first lady Melania Trump before being named last week as the successor to Sarah Sanders, whose last day at the White House was Friday. The first lady disclosed the news in a Twitter message.
Departing press secretary Sarah Sanders followed with a message of support for Grisham.
The Associated Press contributed to this report.