The 37-year-old, who played foreign exchange student Nadia in the first two instalments of the comedy franchise, told WENN that she would not commit to the project until a storyline had been finalised.
She explained: "I haven't signed on to it. I haven't seen a script so I don't know what I'm doing right now. They've been talking to us but as of right now, I'm not signed on."
The planned movie, tentatively titled American Reunion, is expected to follow the original characters as they come together for the 10th anniversary of their high school graduation.
Elizabeth is the only main cast member currently missing from the project after Chris Klein agreed to star alongside the likes of Jason Biggs, Alyson Hannigan and Seann William Scott last month.
American Reunion is scheduled to hit cinemas on April 6 2012.
Watch the trailer for the original American Pie below.