The woman heaved her ceramic mug of English Breakfast tea at the famous canvas in front of security guards at the Louvre Museum, The Daily Mail reported.
The mug bounced off the bullet-proof glass and shattered on the floor in the incident that occurred Aug. 2, but only now was reported, a security guard said.
"There was no damage done to the painting whatsoever," a museum spokesman told the British newspaper. "It is protected by bullet-proof glass ... and also contained in a special sealed box to protect it from vibrations and humidity. It is one of the most well guarded works of art in the world, and it would take more than a well-aimed teacup to damage it."
Two museum security guards subdued the woman, turning her over to police, officials. She reportedly has undergone psychological exams, the newspaper said.
"We are still establishing her state of mind at the time, though there is a possibility she could be charged with criminal damage," a police spokesman said.