What began as a weekend controversy over White House press secretary Sarah Sanders being asked to leave a Virginia restaurant because of her political views has now turned into a war of words between Rep. Maxine Waters and President Donald Trump – who tweeted again Monday that Waters is an "an extraordinarily low IQ person."

Waters, a California Democrat, called on her supporters at a rally on Saturday to confront Trump Cabinet officials in public spaces like restaurants and department stores to protest the administration's policies.

"I have no sympathy for these people that are in this administration who know it is wrong what they're doing on so many fronts but they tend to not want to confront this president," Waters said at the rally in Los Angeles.

"For these members of his Cabinet who remain and try to defend him they're not going to be able to go to a restaurant, they're not going to be able to stop at a gas station, they're not going to be able to shop at a department store, the people are going to turn on them, they're going to protest, they're going to absolutely harass them until they decide that they're going to tell the president 'no I can't hang with you, this is wrong this is unconscionable and we can't keep doing this to children,'" she continued.

"Let's make sure we show up wherever we have to show up. And if you see anybody from that Cabinet in a restaurant, in a department store, at a gasoline station, you get out and you create a crowd. And you push back on them. And you tell them they're not welcome anymore, anywhere. We've got to get the children connected to their parents," Waters said.

Trump blasted Waters on Twitter on Monday.

“Congresswoman Maxine Waters, an extraordinarily low IQ person, has become, together with Nancy Pelosi, the Face of the Democrat Party. She has just called for harm to supporters, of which there are many, of the Make America Great Again movement. Be careful what you wish for Max!” Trump said.

Waters had had no response to Trump's tweet as of Monday afternoon.

Waters’ call to action comes on the heels of widespread outrage over the Trump administration's policy of forcibly separating migrant families who illegally cross the southern border from Mexico.

Trump signed an executive order last week to end the practice of separating migrant families. But well over a thousand children remain apart from their parents, and many continue to criticize the president's "zero tolerance" approach to illegal immigration.

Waters’ comments were swiftly criticized by members of both parties in Congress. On Monday, House Minority Leader Nancy Pelosi tweeted a subtle rebuke aimed at her Democratic House colleague.

“In the crucial months ahead, we must strive to make America beautiful again. Trump’s daily lack of civility has provoked responses that are predictable but unacceptable. As we go forward, we must conduct elections in a way that achieves unity from sea to shining sea,” Pelosi tweeted.

And Republican Sen. Jeff Flake of Arizona tweeted, “Left or right, nobody deserves this kind of treatment,” in reference to Waters’ comments.

Sanders violated ethics laws when she used her official White House Twitter account to complain about getting kicked out of a Virginia restaurant, according to the former head of the U.S. Office of Government Ethics.

“Sarah, I know you don’t care even a tiny little bit about the ethics rules, but using your official account for this is a clear violation of 5 CFR 2635.702(a). It’s the same as if an ATF agent pulled out his badge when a restaurant tried to throw him/her out,” Walter Shaub, the former ethics chief, said in a tweet.

He went on to explain: “Sanders used her official govt account to condemn a private business for personal reasons. Seeks to coerce business by using her office to get public to pressure it. Violates endorsements ban too, which has an obvious corollary for discouraging patronage. Misuse reg covers both.”

“Her goal was transparently to get her fans to boycott or harass the restaurant, and that is exactly what has happened. If you were teaching ethics training, you’d never offer this as an example of what is acceptable. It’s like when Trump attacked Nordstrom,” Shaub tweeted.

Rep. Barbara Lee, D-Calif., called on the OGE to investigate Sanders for using her official Twitter account to attack the restaurant.

"She used her government account for taking on this private restaurant, a private business," Lee said on CNN Sunday. "I personally think she should be referred to the Office of Government Ethics."

Sanders explained on Twitter Saturday that she "was told by the owner" of the Red Hen Restaurant in Lexington, Virginia to leave because she worked for the president.

"Her actions say far more about her than about me," she added. "I always do my best to treat people, including those I disagree with, respectfully and will continue to do so."

Trump jumped to the defense of his press secretary after a Virginia restaurant kicked her out this weekend, saying the "filthy" restaurant should focus more on cleanliness.

“The Red Hen Restaurant should focus more on cleaning its filthy canopies, doors and windows (badly needs a paint job) rather than refusing to serve a fine person like Sarah Huckabee Sanders. I always had a rule, if a restaurant is dirty on the outside, it is dirty on the inside!” Trump said.

Trump provided no evidence to support his description of the restaurant and a photo taken of the restaurant this weekend appears to show a clean, well-maintained building.

Shaub said Trump's tweet may have violated ethics laws, too.

"p.s. Trump’s Red Hen rant would also violate the misuse of position regulation, if he followed the tradition of trying to act as though it applied. But this walking conflict of interest has chosen to hold himself to a lower standard than the federal workforce he supervises," Shaub tweeted.

The barn-red establishment passed its most recent health inspection Feb. 6 of this year, according to the state's health inspection database. The Red Hen had no violations.

Sanders wasn't the first official to be personally confronted with public anger over the administration's immigration policy. Homeland Security Secretary Kirstjen Nielsen, who oversees the nation's borders, was bombarded by protesters on Tuesday night while she dined at an upscale Mexican restaurant in Washington, D.C.

Video of the confrontation was posted to Facebook.

The protesters, members of Metro DC Democratic Socialists of America, loudly booed at Nielsen and repeatedly shouted "shame."

"Secretary Nielsen, how dare you spend your evening here eating dinner as you're complicit in the separation and deportation of over 10,000 children separated from their parents," one protester yelled. "How can you enjoy a Mexican dinner as you’re deporting and imprisoning tens of thousands of people who come here seeking asylum in the United States?"

ABC News' Kendall Karson contributed to this report.