Eighteen anti-war activists came to the campaign offices for Rudy Giuliani and Hillary Rodham Clinton to demand the candidates to withdraw American soldiers from Iraq if they are elected for president. All of them were arrested.
The protesters were charged with trespassing and taken to the Polk County Jail, police said. One minor was released.
Frank Cordaro, a former priest who helped plan the protests, said the activists occupied both offices for a few hours, banging on desks and shouting their demands.
"We're making some great street theater," Cordaro told The Associated Press, the sounds of banging and chanting in the background.
Ten people were arrested at Republican Giuliani's office in Clive; the rest were arrested several hours later at Democrat Clinton's office in Des Moines .
Cordaro said his group decided to protest against Clinton and Giuliani because they are the biggest supporters of the Iraq war among the presidential candidates in next year's election.
Clinton aide Mark Daley defended his candidate, calling her a war opponent but offering no timetable for a troop withdrawal. A Giuliani spokesman, Jarrod Agen, said the protests will not affect Giuliani's stance on the war.
The arrests follow similar protests in recent months in the state offices of Iowa Sens. Chuck Grassley and Tom Harkin. Those demonstrations prompted almost two dozen arrests in Des Moines and Cedar Rapids .