US President Donald Trump has stepped up his war of words with Democrats after his spokeswoman was kicked out of a restaurant by its anti-Trump owner.
Democratic lawmaker Maxine Waters encouraged supporters to publicly harass Trump administration officials during a rally on Saturday.
On Monday, Mr Trump warned Ms Waters in a tweet: "Be careful what you wish for Max."
Top Democrat Nancy Pelosi has chided Ms Waters, as well as Mr Trump.
In his tweet on Monday, Mr Trump called Ms Waters a person with "an extraordinarily low IQ" who had "called for harm" to his supporters.
The controversy began on Friday night, when White House press secretary Sarah Sanders was kicked out of the Red Hen restaurant because of her work for President Trump.
At a rally in Los Angeles on Saturday, Ms Waters encouraged people to act against the Trump administration in similar ways.
"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," she said at the event, which was filmed and shared on YouTube.
"You tell them they're not welcome anymore, anywhere," the California congresswoman said, calling for Mr Trump's impeachment during the same speech.
During an interview on MSNBC after the rally, Ms Waters encouraged Americans to "harass them [Trump administration officials] until they decide that they're going to tell the President, 'no I can't hang with you'".
Earlier on Monday, President Trump posted a tweet rubbishing the restaurant that threw out his press secretary.