BANGKOK — Antigovernment protesters broke into and briefly occupied the grounds of Thailand’s army headquarters on Friday, capping a week of dramatic and provocative gestures against the country’s most influential political family.The protests against the dominance of Thaksin Shinawatra, the billionaire tycoon in exile, and his sister, Yingluck Shinawatra, the country’s prime minister, have included seizing of the Finance Ministry, cutting power to Police Headquarters and the occupation of a large government facility.

The protests are the largest in the country since a military crackdown left more than 90 people dead three years ago. This time the government and the military have been strikingly restrained in their reaction. The government says this is a deliberate strategy of nonconfrontation to avoid violence.We have not arrested a single protester so far,” Maj. Gen. Piya Uthayo, a police spokesman, said by telephone. Arresting protesters is “not our policy,” he said.

Clashes between demonstrators and the police have been minimal, despite provocations by protesters. Protesters deflated the tires of police vans and were said to have used slingshots against a police officer, whose bloodied face was shown in the Thai media.The country’s education minister, Chaturon Chaisang, described Mr. Suthep’s proposal as “more emotional than rational.”

The number of protesters has tapered off since early in the week but remains in the thousands. On Friday, two members of Parliament from the opposition Democrat Party, Abhisit Vejjajiva and Korn Chatikavanij, joined the protests, leading a cortege of well-dressed office workers through the central business district. The protesters delivered a letter to the United States Embassy in response to a statement by the State Department that had expressed concern about the protests.

Mr. Korn, a former investment banker with J.P. Morgan, said Ms. Yingluck’s government was illegitimate because the governing party did not accept a ruling by the constitutional court last week. The court said that the ruling party’s attempt to make the upper house of Parliament a fully elected body — half of its members are currently appointed by senior judges and civil servants — was unconstitutional. The governing party rejected the ruling because it said the court did not have jurisdiction in the matter.

“When the government acts above the law, the people no longer need to respect the government,” Mr. Korn told the crowd as he marched to the embassy.