Dozens of pro-Palestinian protesters charged a line of police in a standoff with hundreds of officers outside the Israeli consulate on the second night of the Democratic National Convention.
After the larger gathering began to disperse, splintering off into smaller groups, other interactions with police led to more than a dozen arrests.
Officers called the demonstrations “an unlawful assembly”.
Earlier, protesters chanted “Let them go!” as police handcuffed at least four people and led them away from Tuesday’s demonstration.
Officers carrying wooden clubs shouted “move” and penned the demonstrators in on the street, preventing them from marching.
Some demonstrators set an American flag on fire in the street as the celebratory roll call for Vice President Kamala Harris took place inside the United Center about two miles away.
Others carried Palestinian flags, while many others wore black and covered their faces.
Dozens of Chicago police officers were posted outside the building, where law enforcement had closed down most of the entrances on Tuesday, allowing commuters to come in only one entrance where armed officers were also posted. Many of the building’s shops were closed.
The sites of demonstrations from the previous night were largely quiet.
Thirteen people were arrested during Monday’s protests, most related to a “brief breach” of security fencing “within sight and sound of the United Center,” the city’s police superintendent said.
The consulate has been the site of numerous demonstrations since the war in Gaza began in October. It is in a building connected to the Ogilvie Transportation Center, a major commuter rail station.
Israel supporters, including some relatives of people kidnapped by Hamas, gathered earlier in the day at a pro-Israel art installation not far from the consulate to call on US leaders to continue backing Israel and pushing for the release of hostages.
The art installation included giant milk cartons bearing photos of some of the hostages.
Elan Carr, chief executive of the Israeli-American Council, condemned the pro-Palestinian protesters who have descended on Chicago this week, calling them “fringe crazies” and demanding that US leaders “stand unequivocally with the state of Israel”.
More protests are planned throughout the week.
Attendance at the main rally on Monday was far below estimates of organisers who had predicted more than 20,000 would show up with Chicago Police Superintendent Larry Snelling saying the crowd was around 3,500 strong and that the vast majority of the protesters were peaceful.
Some clashed with police, used pepper spray against them and threw water bottles at officers during the clash in the park where there was a breach in security fencing, Mr Snelling said.
“Our officers showed great restraint,” he said. “We’re not going to tolerate vandalism and violence in our city. We’re going to continue to protect the city.”
The 13 people arrested during Monday’s protest were detained on charges ranging from criminal trespass and resisting and obstructing an arrest, to aggravated battery of police officers, he said.
At least 10 of them were arrested in connection with breaching a security fence, he said.
Mr Snelling said the vast majority of participants were peaceful.
The Chicago chapter of the National Lawyers Guild said two of the people arrested were taken to hospital. The police superintendent said they were not taken to the hospital for injuries, but “so they could be provided the treatment they needed when it came to their medications”.
Two people were also arrested on misdemeanour property damage and resisting arrest charges during a protest march on Sunday night.
Most of the largest demonstrations have been organised by the Coalition to March on the DNC, which has focused on calling for a ceasefire in Gaza, but smaller protests have popped up around the city.
