The Scotsman penned a four-year contract extension in September, but the team have experienced a lull in terms of results since then.
The Midlands outfit have lost their last five matches in the Premier League, leaving them 15th in the table.
"I never think fireproof, I never think anybody's bomb-proof," Lambert told reporters. "I know football is about trying to get results. It's got nothing to do with my contract. Nothing, not one iota. We've just not clicked and scored goals."
Villa will take on Tottenham Hotspur on Sunday on home turf.