U.S. President Barack Obama pauses as he gives a statement during a press conference in the Brady Press Briefing Room of the White House on August 18, 2014 in Washington, DC. Obama returned early from his vacation in Martha's Vineyard to hold meetings with his national security team and also with U.S. Attorney General Eric Holder in regards to the situation in Iraq and the continuing violence in Ferguson, Missouri. Win McNamee/Getty Images

In a speech Monday, President Obama called on protesters in Ferguson, Missouri, to remain peaceful and said nonpeaceful protesting "stirs chaos."

"We have all seen images of protesters and law enforcement in the streets. The vast majority are peacefully protesting," he said. "But a small minority of individuals are not. It undermines rather than advances justice."

"Our constitutional rights ... must be vigilantly safeguarded," Obama said. At the same time, the president said "there is no excuse for excessive force by police. Ours is a nation of laws."

Obama's speech comes just hours after Dr. Michael Baden, the doctor who performed the autopsy on Michael Brown, the teenager who was shot Aug. 9 in Ferguson could have survived all of his wounds except for the shot that struck the top of his head. According to information released by officials Sunday, Brown was shot at least six times.

Following the Aug. 9 shooting, riots erupted in the streets of Ferguson. Residents clashed with the local police, as well as other law enforcement groups that stepped in. The St. Louis County police took control of the situation following the local police's involvement before the State Highway Patrol stepped in. The clashes, which included the use of tear gas and rubber bullets by the police, escalated over the weekend. As a result, the National Guard was called in and started patrolling the streets Monday afternoon.

Missouri National Guard Brigadier General Gregory Mason said Monday that the soldiers taking over are "well trained and well seasoned" and that they have and are "well equipped to handle this mission." Gov. Jay Nixon said the National Guard will have "limited responsibilities" to help keep order during late-night protests.

Nixon had implemented a curfew in Ferguson over the weekend, but lifted it Monday afternoon after the violence continued.

The U.S. Department of Justice has opened an investigation into the death of Brown. Obama said in his speech that Holder would travel to Ferguson Wednesday to meet with those working on the investigation.