Mohammadi described the beginning of the confrontation.
"The zodiac boats surrounded us. They came close and left again, and helicopters came close and left again. And now, they actually surrounded the boat and attempted to climb into the boat using hooks," she said.
Mohammadi wasn't injured.
Fellow activists say Mohammadi was an organizer for the group Viva Palestina and had been on aid missions to Gaza before.
She was born in Iran and raised in Boise, Idaho. She's a 2005 graduate of the law school at the University of North Carolina at Chapel Hill.
(The Associated Press contributed to this report.)