United came out on top 2-1 thanks to Anthony Martial’s first half opener and Bruno Fernandes’ penalty in the second half after Bertrand Traore had equalised for the visitors.
Smith’s complaints came after Douglas Luis was adjudged to have fouled Paul Pogba in the penalty area, with referee Michael Oliver sticking by his original decision to award the home side a spot kick despite a VAR review.
Smith is adamant no foul was committed on Pogba as the Frenchman tripped himself in the danger zone.
“I thought it was a penalty at the time, but I looked at it after the game and saw he tripped himself. I don't see why [referee] Michael Oliver couldn't have looked at it. That's what VAR is for isn't it?” Smith told Sky Sports.
“He's tripped himself up. There are margins in football. I've seen it again, and I don't think it's a penalty.”
“First half we were miles off it. The first 15 minutes felt like a testimonial,” he added on his assessment of the game.
“Then they injected some pace into it and deservedly went ahead.
“I asked for more at half-time and we deserved to get back in the game. Our goalkeeper has had to make some good saves but they were all outside the box.
“We know we're on a good journey at the moment. We believe we've got five key arrivals to go with the players who are Premier League ready now.
“This is only our second season in the division, but competing here and against Liverpool and Arsenal shows our journey is going well so far.”
Villa remain in sixth position on the Premier League table and host Liverpool in the 3rd round of the FA Cup next weekend.
