Skyline High School Principal Tom Stumpf said American flags were brazenly waved in the faces of Hispanic students and in one case a Mexican flag was thrown into the face of another student.
"When it involves the American flag and its abuse in vilifying other people, we simply will not tolerate it," Stumpf said. "They were using the symbol derisively as misguided patriotism."
Students were warned about the policy Friday and several were suspended, although Stumpf would not provide details. Then, about 100 students protested during lunch time.
Student Dustin Carlson told Denver station KCNC-TV that he was suspended for two days.
"I'm getting suspended for it and personally I think that's uncalled for," he said. "If this country means freedom, then why can't we fly our own flag? It's ridiculous."
On Monday, about 150 high school students, including some from Skyline, protested in Longmont.
"People are taking it to a whole other level," said Laura Avitia. "I don't think they know why we were protesting."
Thousands of high school students Friday in California, Texas, Nevada and other states protested the tough immigration laws proposed in the House. Some waved Mexican flags and carried signs saying "We are not criminals."
Students in California, Texas, Nevada and other states held demonstrations Friday. Most were peaceful, but there was a stabbing during a protest in Virginia and another student was arrested in Las Vegas.
The student protests coincided with a , where President George W. Bush, Mexican President Vicente Fox and Canadian Prime Minister Stephen Harper are embroiled in an intense debate over immigration legislation.
The protests were also intertwined with the 79th anniversary of the birth of the late Cesar Chavez, the co-founder of the United Farm Workers union who became a champion of poor, Hispanic agricultural workers in the 1960s and '70s.
At San Diego's Chicano Park, students waved Mexican flags and distributed leaflets explaining a provision of a bill approved in the House of Representatives that calls for a sweeping crackdown on illegal immigration.
A police spokesman said there were about 1,500 protesters at the park, although a school district spokeswoman put it near 2,000.
Jessica Hurtado, a U.S.-born high school senior whose parents came from Mexico and are now legal residents, said the House legislation would "affect pretty much everyone I know: aunts, uncles, friends."
At a protest that drew about 75 people in Virginia's Fairfax County, police said a high school student was stabbed.