Jordan Gernter told X17 that recent rumours that Taryn Manning or Elisha Cuthbert were being lined up to replace the Machete star are "completely and utterly untrue".
"Lindsay's our Linda Lovelace - we're committed to have Lindsay in our movie," he said.
The producer confirmed that production on Inferno would be delayed until Lohan is available to shoot the movie.
"Our lead actress is currently not available, so we will continue to change our schedule until she is."
Location filming may also prove difficult because the actress may be restricted from travelling outside the state of California after her next probation violation hearing.
Gertner explained: "We haven't decided on a shooting location, but it will all depend on Lindsay."
The next court hearing in the case of Lohan's recent drug test failure will be held on October 22.