The 28-year-old singer said she is not happy when her nieces' dance moves are influenced by performances of these singers, reported Contatcmusic.
"I've met them both and that is them - they're not putting on an act and no one is telling them what to do," Lewis said.
"I have a lot of respect for them, but because I have nieces and I've seen my six-year-old goddaughter doing dance moves that she shouldn't, it does not impress me and I tell her to stop," she added.