The Birmingham outfit have lost five straight league games, conceding 18 goals, after a shock 3-1 win at Liverpool on 15 December.
Villa have been linked with Manchester City’s out-of-favour defender Joleon Lescott and Swansea City striker Danny Graham over the past week.
But Lambert, who has relied on Villa’s promising youngsters this season, says he does not have a big budget at his disposal this month, instead hinting at possible loan deals.
“There is a chance of no signings at all. There is also a chance you might try and get someone in, so it works both ways,” Lambert said.
“We’d try to do something if I thought the people we could get in would make it better.
“But if we can’t do it, and I have to go with the group that’s there, then I’ll go with what’s there. What I don’t want to do is fill the place with people I’m bringing in just for the sake of bringing them in.
“A £15m spending spree is not on the agenda, nowhere near it.
“Loans are not something I’d disregard. I’ll just have to wait and see on that as well.”
Villa face derby rivals West Bromwich Albion at the Hawthorns on Saturday.
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