"Totally clueless," one person commented on the image.
"What an eff-ing disgrace! How far we've fallen in only a year!" another added.
"Incredibly tacky and an insult to the position of First Lady. #embarassing," another tweeted.
But there were some who praised the snap, saying the First Lady looked "beautiful".
"She is gorgeous, these jealous people need to get over it," one person wrote.
"Jealousy is a sad thing, she is gorgeous. The only thing wrong with some of you is you wish you had it, leave her alone and get over it," another added.
Earlier on Christmas Eve, the White House released a photo of President Trump and the first lady making phone calls to children across the US as part of the traditional NORAD tracking of Santa's trip around the globe.
"POTUS and I had fun helping children track Santa tonight," the first lady tweeted. "Wishing everyone a wonderful Christmas Eve."
On Christmas Day, Trump released a message as well, posting a video to Twitter in which he said: "In the season of joy, we spend time with our families, we renew the bonds of love and goodwill between our citizens and most importantly we celebrate the miracle of Christmas.
"For Christians we remember the story of Jesus, Mary and Joseph that began more than 2000 years ago. As the book of Isaiah tells us, for to us a child is born, to us a son is given and the government will be on his shoulders and he will be called wonderful counsellor, mighty God, everlasting father, prince of peace. This good news is the greatest Christmas gift of all, the reason for our joy and the true source of our hope."
The president tweeted again on Monday evening.
"I hope everyone is having a great Christmas, then tomorrow it's back to work in order to Make America Great Again (which is happening faster than anyone anticipated!"
