Washington DC - First lady Melania Trump made a rare political intervention Tuesday with a tone-deaf call for "unity" amid widespread fury at killings carried out by immigration agents in Minneapolis.

In an interview to promote the release of her self-titled documentary this week, the Slovenian-born former model appeared to put the blame on demonstrators by calling for them to "protest in peace."

Her husband, President Donald Trump, has sought to pivot amid a growing backlash over the killing on Saturday of Alex Pretti, the second person shot dead by immigration agents in Minneapolis this month.

"We need to unify. I'm calling for unity," Melania told Fox and Friends when asked for her message about the shootings and the protests in Minneapolis.

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The 55-year-old added that President Trump had a "great call" with the Democratic governor of Minnesota and mayor of Minneapolis "and they are working together to make it peaceful and without riots."

"I'm against the violence, so please, if we protest, protest in peace, and we need to unify in these times," she said, speaking against a backdrop of the logo for her movie, titled Melania, which was screened at the White House just hours after Pretti, a 37-year-old nurse, was gunned down by Border Patrol agents.

The movie has its premiere at the Kennedy Center in Washington – recently renamed the Trump-Kennedy Center by a board handpicked by the Republican president – on Thursday.

It is released in cinemas on Friday. Reports put Amazon's licensing deal for the film at around $40 million.

Top Trump officials initially called Pretti a "terrorist" and "assassin," but the White House distanced itself from that language on Monday as footage emerged showing that the victim was shot after agents had already removed a side arm he was legally licensed to carry and never brandished.