E! Online said Hanks is supporting the tentative agreement the smaller of the two major actors unions has arrived at with the Alliance of Motion Picture and Television Producers because he wants to help avoid an actors' strike.
The recent three-month-long Writers Guild of America strike against the AMPTP shut down most of the U.S. television industry and caused several film projects to be postponed or scrapped.
Hanks's film "Angels and Demons" was one of the movies pushed back due to the strike.
The AMPTP and the other actors' union, the Screen Actors Guild, have been trying to hammer out a new contract for weeks, but as yet have not been able to reach an agreement.
"Either our employers will lock us out, or SAG will strike," states the petition Hanks signed. "There really is no alternative if the AFTRA deal is defeated."
E! Online said James Cromwell, Adam Arkin, Morgan Fairchild and Tess Harper have also signed the AFTRA petition.
SAG's current contract expires June 30.