Trump, while remarking on the age and achievements of some of the veterans, known as code talkers, took the chance to mock the Massachusetts Democrat.
"You were here long before any of us were here," Trump said at the White House. "Although we have a representative in Congress who they say was here a long time ago. They call her Pocahontas."
The remark was met with silence. Trump lobbed the name at Warren with three Native American veterans sitting and standing next to him. He stood directly in front of a portrait of President Andrew Jackson, whose administration is widely criticized for its treatment of Native Americans.
Trump has called Warren the name because of her claimed Native American heritage. The senator, a frequent Trump critic, told MSNBC on Monday that Trump's comments under the circumstances were "deeply unfortunate."
"This was supposed to be an event to honor heroes, people who put it all on the line for our country. ... It is deeply unfortunate that the president of the United States cannot even make it through a ceremony honoring these heroes without having to throw out a racial slur," Warren said.
The code talkers used their native languages during World Wars I and II to confuse American enemies attempting to break codes.
Later Monday, Navajo Nation President Russell Begaye said the remark was unfortunate.
"In this day and age, all tribal nations still battle insensitive references to our people. The prejudice that Native American people face is an unfortunate historical legacy," Begaye said in a statement.
While the Navajo Nation appreciated the honor and recognition bestowed upon its "code talkers," Begaye said, it does not want to be a part of this "ongoing feud" between the senator and the president.