Lewis' camp says it is pressing Tyson and to sign-up for the bout - due to take place on June 21 - by the end of next week.
A clause in the original fight contract allowed for a rematch - with the fight likely to be another big hit on pay-per-view.
Talks between rival networks HBO - which represents Lewis - and Tyson's Showtime, have been on-going and now pressure is being applied to the cable TV network to get a deal signed.
Said Lewis' business manager Adrian Ogun: "We are working to a very, very tight schedule with regard to a rematch with Mike Tyson so we have to have a formal response back from Showtime and Tyson by the end of next week."
"At the moment Lennox is exploring all his options and they include fighting and not fighting and all the possible consequences. The conditions have got to be right for him."
Lewis and Tyson are both thought to be considering retirement after their final money-spinning bout. However, should Tyson pull out, then Lewis could yet face Vitali Klitschko.
