"There's no message. I hope we can talk about her important visit with children today rather than her wardrobe choice".
She visited the Upbring New Hope Children's Center there.
The White House responded to criticism by saying there was no hidden message.
It was Trump's idea to go to the border to see firsthand how migrant children are being treated, her husband said.
While Grisham insists that today's choice of attire did not have a "hidden message", others have pointed out that in the past, Trump's fashion decisions were, in fact, poignant.
It moves parents with children to the front of the line for immigration proceedings, but the Trump administration said it did not end the 10-week-old zero tolerance policy that calls for prosecution of immigrants crossing the border illegally under the country's criminal entry statute.
First Lady Melania Trump made a surprise visit to a Texas detention center Thursday.
Melania Trump wearing a Zara design jacket with the phrase "I really don't care".
"It's a jacket", Stephanie Grisham, Melania Trump's spokeswoman, told reporters.
In allowing journalists to accompany her, Melania Trump ensured that her meetings with immigrants would be well publicised. But I forgot that this is the darkest timeline and, indeed, soon the jacket was confirmed by Trump's own spokesperson who said: "It's a jacket". One outraged user borrowed an image of the back of the jacket to promote groups working on behalf of immigrant children. "She wanted to see as close to what she had been seeing on TV".
Visiting another classroom, Melania asked children where they were from and how long they'd been at the centre where staff said children typically spend between 42 and 45 days. Last August, the media and public discussed the high-heeled shoes she wore to fly to Texas to view Hurricane Harvey destruction.
But upon returning to the White House she sported the jacket once more, despite stifling heat and humidity in the Washington region.