Royal Australian College of General Practitioners president Harry Nespolon said Evans should "stick to talking about 'activated almonds' and leave vaccinations alone".
"Vaccinations save lives and it is intensely frustrating that individuals like Pete Evans are trying so hard to cause so much harm," Nespolon told news.com.au.
"Vaccines are one of the great success stories of modern medicine but the rise of the anti-vaxxer trend has eroded some of these gains and lead to needless death and suffering.
"Robert F Kennedy is not doing 'important work' for coming generations; he is perpetuating dangerous, anti-scientific myths which are causing tremendous harm in countries including the United States and Australia."
Many Australians look up to Evans in his role as a celebrity chef and TV star, Nespolon said.
"I hope that he rethinks the company he keeps and books an appointment with his local GP to learn about the damage he is doing promoting the 'Children's Health Defence'."
Associate Professor Margie Danchin is the leader of the vaccine uptake research group at the Murdoch Children's Research Institute and said Evans' promotion of Kennedy's group is "very concerning".
"It's extremely damaging when celebrities like Pete Evans come out and align themselves with prominent vaccine deniers like Robert Kennedy, whose organisation is very strongly anti-vaccination," Danchin said.
"It seems to be every other week that a celebrity will get up and have strong anti-vaccination views and what they're doing is eroding trust in medicine and science.
"Celebrities carry a lot of weight and influence. It has a powerful impact on the public. It's very concerning. It's important for us vaccine experts to come out very strongly and counter the arguments that vaccine deniers spread."
She said the science on vaccinations is settled and every claim presented by anti-vaxxers has been universally debunked.
"The science is crystal clear. We know that vaccines work and they save lives," she said.
"It's important to acknowledge that there are potential side effects from vaccines, like with any medicine, but the majority are mild and rare.
"There are a few very rare adverse events but they're extremely uncommon. On balance, the benefit of vaccines far outweighs the minimal risk."
Sydney GP Brad McKay slammed Evans for his latest foray into medicine, saying the community "has tolerated his anti-science rantings for long enough".
"Pete Evans has peddled nonsense for years," McKay said.
"Protecting himself from harmless Wi-Fi with a magical 'earthing mat', avoiding fluoride toothpaste because he believes tiny amounts are toxic – they're not – and abstaining from milk because he reckons it causes osteoporosis, – it doesn't. He needs to stop."
Promoting Kennedy and linking to his organisation is dangerous, McKay said, and contributing to an "undermining of important public health efforts".
"Pete Evans' status as a celebrity chef with a national television show gives him credibility among his followers, but when it comes to health advice their trust is misplaced.
"He's not a health professional."
One of the first comments on Evans' post on Instagram was from Frank Winterstein, the NRL star who with his wife Taylor are prominent voices in the anti-vaxxer movement.
Taylor Winterstein has been vocal about Samoa's effort to inoculate people in the wake of the recent measles outbreak there, where misinformation has seen vaccination rates decline.
She met Kennedy in Samoa last June in the midst of the outbreak crisis. There have been more than 5000 cases of infection in the Pacific nation and 80 people died.
"Mainstream media are doing their best to use my family as a scapegoat for the Samoan Government, they want us to carry the blame, they want to distract the public from what is really going on," she said in December.
She had previously compared Samoa to Nazi Germany after it announced compulsory vaccinations and adopted strict containment policies.
Danchin said there was a wealth of information about vaccinations that was based on science and evidence that people should prioritise over the views of untrained and inexperienced celebrities.
"The National Centre for Immunisation Research and Surveillance has good fact sheets on its website for starters.
"And we know that the most important thing a person can do if they have questions about vaccinations is to speak to their healthcare practitioner."
It's advice echoed by Nespolon, who urged people to ignore celebrities and seek out professionals.
"For anyone potentially persuaded by Mr Evans' Instagram post my message is simple – this isn't just about you and your children.
"We can only achieve herd immunity and stop the re-emergence of diseases that had earlier been eliminated such as measles if all children's vaccinations are up to date."
Evans, who is the face of My Kitchen Rules and a prominent paleo diet advocate, has attracted condemnation for a number of dubious health claims.
He claimed in a Netflix documentary that the keto diet could assist people with autism, asthma and even cancer. His views on sunscreen and fluoride have also been attacked.
Evans did not respond to a request for comment.
