Airport security officers carried the woman away by the feet and arms as she protested her removal.
She later identified herself as Brenda Lee, a writer for the Georgia Informer in Macon and said she has White House press credentials. The newspaper's Web site says it is a monthly publication, and a Brenda Lee column is posted on it.
Calls to the newspaper and the White House press office were not immediately returned.
Lee said in a telephone interview with The Associated Press that she wanted to hand Obama a letter urging him "to take a stand for traditional marriage."
She said she asked a Secret Service agent to give the president her letter, but he refused and referred her to a White House staffer. Lee said she refused to give the staffer the letter.
"I said, 'I'll take my chances if (the president) comes by here,'" said Lee, who identified herself as a Roman Catholic priestess who lives in Anaheim, Calif. "He became annoyed that I wouldn't give him the letter."
Lee, who was wearing what she described as a cassock, said she protested when she was asked to leave.
"I said, 'Why are you bothering me?' They escorted me outside the gate," she said.