The world number five announced Sunday that he will start with Roselyne Bachelot, who served as the French minister of health and sports between 2007 and 2010.
Last week, Bachelot accused Nadal of taking seven months out of tennis between 2012 and 2013 to cover up a failed drugs test.
The Spaniard says he missed out on various tournaments, including the 2012 Olympics and U.S. Open, because of a knee injury.
"I am going to sue her, and I am going to sue everyone who is going to comment something similar in future, because I am tired of that," Nadal said at the Indian Wells tournament.
"I let it go a few times in the past. No more."
A representative from Nadal's Monaco-based PR team, Benito Pérez-Barbadillo, told CNN: "Rafa was very clear ... he will definitely take legal actions. His lawyers are studying how to proceed."
The 14-time grand slam winner, who beat Gilles Muller in straight sets on Sunday to reach the third round in California, has never failed a drugs test in his career.
"We know that the famous injury which kept Nadal out for seven months is without any doubt because he tested positive," Bachelot told Canal+. "When you see a tennis player out of action for a long time, it's usually because they've tested positive."
CNN has attempted to contact the 69-year-old Bachelot but she was not immediately available for comment.
Bachelot was speaking in the wake of Maria Sharapova's shock positive test for meldonium, which was added to the banned list by the World Anti-Doping Agency (WADA) this year.
Sharapova failed a drug test on January 26 after losing to Serena Williams in the quarterfinals of the Australian Open, and could face up to a four-year ban from the sport.
Nadal, who said Sharapova 'must pay' for her actions
despite hoping that the Russian had made an innocent mistake, outlined his views on doping last week.
"I am a completely clean guy," the 29-year-old said. "I worked so hard during my career that when I get injured I never take nothing (banned) to be back quicker."
The International Tennis Federation (ITF) has labeled Bachelot's allegations as "surprising, but also incorrect."
"All players who are convicted of a violation of the Tennis Anti-Doping Program are publicly announced as required under the rules of the Program and WADA," the ITF said in a statement sent to CNN.
"WADA has independent oversight of the results of all samples that are collected from tennis players under the Program and so would not only be aware of any attempted coverup or failure to act on any positive test, but also have the right to appeal against any failure to take forward any apparent breach of the Program."
Nadal has received widespread support since Bachelot's comments.
One of his backers is Real Madrid's French manager Zinedine Zidane, who said he felt bad for one of the club's more famous fans.
"He is a gentleman and has always made his values clear, which everybody appreciates. I feel bad about what has been said."
Meanwhile, Spain's National Olympic Committee announced it 'deeply regretted the unfortunate and unjustified statements' from Bachelot.
"Given the position she has held, she should be aware that such accusations -- given their importance -- must be backed up by evidence that substantiates them and which should be presented to the relevant bodies for knowledge and action," it said in a statement.