NEW YORK — Anti-Wall Street protesters exulted Friday after beating back a plan to clear them from the park they have occupied for the past month. But that didn't prevent a brief clash with police that led to 15 arrests.

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The showdown in New York came as tensions were rising in several U.S. cities over the spreading protests, with numerous arrests and scattered clashes between demonstrators and police.

The owners of Zuccotti Park in lower Manhattan had announced plans to temporarily evict the hundreds of protesters at 7 a.m. Friday so that the grounds could be powerwashed. But the protesters feared it was a pretext to break up the demonstration, and they vowed to stand their ground, raising the prospect of clashes with police.

Just minutes before the appointed hour, the word came down that the park's owners, Brookfield Office Properties, had postponed the cleanup. A boisterous cheer went up among the demonstrators, whose numbers had swelled to about 2,000 before daybreak in response to a call for help in fending off the police.

NBC News reported that police used the scooters to try to force protesters off of the street at several locations on Wall Street and Broadway.

Despite police efforts, some protesters managed to gather at the Stock Exchange, NBC News said.

In some cases, police rode scooters directly at people who stopped traffic and refused to move away.

Demonstrators threw bottles and one threw a garbage can at police, according to reporters on the scene.

Police arrested 15 people, including protesters who obstructed traffic by standing or sitting in the street, and others who turned over trash baskets and hurled bottles. A deputy inspector was sprayed in the face with an unknown liquid.

Mary Altaffer  /  AP

A New York City police officer runs over a National Lawyers Guild observer as Occupy Wall Street demonstrators march through the streets near Wall Street, Friday.

In one case, an observer with the National Lawyers Guild who was marching with the group refused to move off the street for police, and his foot was run over by an officer's scooter. He fell to the ground screaming and writhing and kicked over the scooter before police flipped him over and arrested him.

In a statement, Brookfield said it decided to delay the cleaning "for a short period of time" at the request of "a number of local political leaders." It gave no details.

Brookfield said it would negotiate with protesters about how the park should be used. But it was unclear when those discussions would occur.

Though the park is privately owned, it is required to be open to the public 24 hours per day.

First Read: Americans' views on 'Occupy Wall Street'

Brookfield, a publicly traded real estate firm, had announced plans to powerwash the plaza section by section over 12 hours and then allow the protesters to return. But it said it would begin enforcing the park's rules against tents, tarps and sleeping bags, complaining the grounds had become unsanitary and unsafe.

The New York Police Department had said it would make arrests if Brookfield requested it and laws were broken.

As the morning deadline drew near, some protesters rushed to scrub and sweep the park and pick up trash in hopes of preventing a crackdown.

Mayor Michael Bloomberg, whose girlfriend is on Brookfield's board of directors, said his staff was under strict orders not to pressure the company one way or the other. He noted that Brookfield can still go ahead with the cleanup at some point.

Story: Old guard back in the trenches at 'Occupy' protests

"My understanding is that Brookfield got lots of calls from many elected officials threatening them and saying, ... 'We're going to make your life more difficult,'" he said on his weekly radio show.

Over the past month, the protest against corporate greed and economic inequality has spread to cities across the U.S. and around the world. Several demonstrations are planned this weekend in the U.S., Canada and Europe, as well as in Asia and Africa.

In other U.S. cities:

• Denver police in riot gear herded hundreds of protesters away from the Colorado state Capitol early Friday, arresting about two dozen people and dismantling their encampment.
• Trenton, N.J., protesters were ordered to remove tents near a war memorial.
• Organizers in Des Moines, Iowa, warned of a possible "big conflict" Friday night after the state denied their permit to continue overnight protests at the Capitol.
• San Diego police on Friday used pepper spray to break up a human chain formed by anti-Wall Street demonstrators at a downtown plaza where they've camped for a week.
• Police in Seattle confirmed that they had arrested 10 people on Thursday.