Bent is currently sidelined by an ankle problem, but had lost his place in Lambert's Premier League starting line-up to Christian Benteke prior to his injury.
His demotion to the substitutes' bench had prompted speculation that Villa could offload their record signing in the New Year, with Fulham linked with a bid.
However, Lambert is adamant that there are no issues with the England international and he is not trying to cash in on Bent.
"I'm not actively looking to sell him," said Lambert.
"There isn't an issue, at least not at my end. It's just back to the injury and I have to look after another 20 lads.
"I have to pick a team I think will win. I've always done that. Everyone has to show their worth. I have no favourites. I judge them as equals."