In a blog post, Sharpe said the announcement was "a backward step" that, if adopted, would be "a triumph of fear and false promise [over] good sense".
"I add my voice to the many that understand that the Federal Government's proposals to filter the Internet are a waste of time, a waste of money, a false promise to parents that will not stop kids being exposed to undesirable content online [and] a move towards censorship that a democratic and free nation like Australia should reject," she said.
Sharpe said the proposed filter created a "diversion" from tackling broader issues such as how the online environment was "rapidly changing social norms, expectations and behaviour".
While she conceded that protecting children from inappropriate material was an issue, Sharpe did not believe a mandatory filter was the answer.
"The solutions include the far more difficult, time consuming and gradual process of education for all citizens, especially parents and kids, greater policing and investigation, greater resourcing to support families and communities and continuous law reform in the areas of privacy and communications," she said.
"I urge the Federal Government to consider other options rather than this proposal."