According to Pop Eater, Palin - who recently denied rumours of "diva"-like behaviour on the set of the ABC series - demanded that show producers forbid Johnston admission to attend.
"The last thing in the world Bristol wants is to look up from her cha cha cha and see his big goofy grin looking at her," a source said.
"This is her time to shine and she doesn't want him trying to steal her spotlight."
Another insider added: "I wouldn't put it past him to try and sneak into a taping. The only person that loves the press more than the Palins is Levi himself."
However, executives at ABC have promised to make sure that no problems arise.
"Security is very tight at Dancing With The Stars," a spokesman for the network insisted.
"If someone is not wanted in the ballroom, I can assure you they will not get in."
Dancing With The Stars premieres September 20. (taheena)
