Benteke has been linked with a move away from Villa Park after scoring 22 goals in his debut season in England, but Lambert has insisted that no figure will be placed in his contract in an attempt to discourage potential interest.
The 43-year-old told the Birmingham Mail: "I don't think you can put any figures in because it just creates problems.
"It's not something I've ever thought about with him. To be fair to Christian, he's never ever said anything about contracts or anything."
The Belgium international scored a hat-trick on Monday as Villa recorded a 6-1 victory over Sunderland.