Loic Remy's 92nd-minute effort handed Newcastle a dramatic victory at St James' Park on Sunday as the home side ended a 450-minute run without a Premier League goal.
But Lambert insists the result was harsh on Villa, who created a number of chances.
He said: "I thought we deserved at least a point, especially after the first half showing.
"I thought we were excellent in that first half. Second half Newcastle came out stronger but I don't think either team deserved to win the game, but we made an error with 30 seconds to go."
The Scot was also quick to praise the contributions of Ashley Westwood and Ryan Bertrand, who both had to be hauled off in the second half due to injury and illness respectively, a factor that Lambert thinks helped to change the game.
He added: "He (Westwood) had a dead leg, which was a pity because I thought he was by far the best player on the pitch.
"I thought he was fantastic with the way he played and to lose him was a blow.
"We also lost Ryan. He had a virus (on Saturday night) so we got the best out of him for 75 minutes, so the two of them coming off were big for us."
Defeat means Villa have lost three of their last four games in the Premier League.
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