Lays Laraya breached Australia's Biosecurity Act for failing to declare the rose, 9News newspaper reported.
Upon arrival at Perth Airport, she was randomly screened by two security officials who asked to see her passenger card, which all arrivals into Australia must complete to pass through customs.
Officials found she had not declared the rose in the passenger card's plant section, though she claimed that she did not know she had to.
Australia has some of the strictest biosecurity rules in the world and plants must be declared.
She claimed she received the rose from a cabin crew member on a Qatar Airways flight while en route to Australia.
After landing at Perth airport, she held the rose in her hand because she did not want to spoil it, she said.