According to TMZ, the former model's lawyer Dan Horowitz announced the decision not to press charges in order to change the existing custody order over the former couple's 19-month-old daughter Lucia.
A source told the website that Grigorieva's change of heart was based on her desire to "extend an olive branch" and resolve the custody battle in a peaceful fashion.
She also reportedly wants to resume normal contact with Gibson, which was previously prevented by a restraining order in place since 2010. The order has since been dropped.
Gibson was previously sentenced to 16 hours of community service and one year of counselling resulting from his no contest plea in the misdemeanor battery charges that Grigorieva brought against him last year.
She later filed a follow-up suit, which the Braveheart actor claimed that he would fight by counter-suing Grigorieva for extortion.
Mel Gibson breaks silence over Oksana tapes