"While we regret the AAA decision, we are more committed than ever to provide the absolute best in hospitality as we have done for the past 235 years," Kmiec said.
The ratings are based on unannounced on-site property evaluations by AAA inspectors.
AAA spokeswoman Heather Hunter said AAA doesn't discuss individual ratings or property inspections.
"The Greenbrier is one of the nation's most historic and notable hotels and we are proud to have it as AAA Approved and Four Diamond Rated hotel," Hunter said.
AAA said it awarded five diamonds to 101 U.S. hotels that provide meticulous service, exceed guest expectations and maintain standards of excellence.
Hunter defined four-diamond hotels as being "refined and stylish with upscale physical attributes, extensive amenities and a high degree of hospitality, service and attention to detail."
Joining The Greenbrier resort on the four-diamond hotel list in West Virginia is Stonewall Resort in Roanoke and the Bavarian Inn in Shepherdstown.