The 44-year-old singer hit back after a British plastic surgeon, Dr Ayham Al-Ayoubi, suggested she "showed many signs" of having work done to her face, reported Femalefirst.
"These before and after pics of JLo show many signs of plastic surgery - naturally pretty but now looks amazing," Ayham posted on Twitter.
She responded to the plastic surgeon, who is based in London, saying, "Dr Ayoubi Sorry Sir, but I have never had plastic surgery of any kind."
But following Lopez and her fans' reaction, the medic claimed his assistant was responsible for the tweets.
The 'American Idol' judge had recently revealed that she learnt to stand up for herself from an early age as she was criticised for her appearance and curvy figure early in her career.