PANAMA CITY, JULY 2 -- Rock-throwing antigovernment students battled police today, the third day of disturbances that began with a confrontation between the United States and Panamanian military commander Gen. Manuel Antonio Noriega.

One group of protesters was dispersed by unidentified armed men who sacked and burned a department store belonging to a leading opposition figure.

The current round of pro- and anti-Noriega demonstrations comes after a 10-day lull in antigovernment protests that erupted June 9. Both sides have used more violent tactics in the new disturbances, which began after the U.S. Senate approved a resolution last Friday calling for Noriega to step down.

{Panamanian Foreign Minister Jorge Abadia Aria told reporters that Panama regrets an attack on the U.S. Embassy there by about 5,000 demonstrators who broke away from a progovernment rally Tuesday, United Press International reported. The State Department had warned Panama that the attack, which included Panamanian officials, would damage bilateral relations.

{Abadia blamed the attack on overzealous nationalism of Panamanians angered by the Senate resolution, and said Panama would pay for damage to the embassy, UPI said.

{The Organization of American States approved a resolution Wednesday night in Washington urging continued good U.S.-Panamanian relations but noting that reports indicated "unwarranted interference in the domestic affairs of Panama." Seventeen nations voted in favor, eight abstained and only the United States voted in opposition.}

Noriega, the commander-in-chief of the 20,000-member defense forces, also dominates the nation's political leadership. He has been accused of involvement in electoral fraud, assassination and corruption, and the opposition accuses him of fomenting anti-U.S. protests to deflect attention from those charges.

Today, students barricaded behind upturned desks in the national university hurled rocks at riot police who surrounded the campus. The police did not enter, but fired bullets and buckshot through the fence to disperse the students.

The opposition daily La Prensa reported three students were hospitalized with bullet wounds after the day-long clashes, and dozens suffered buckshot injuries.

At noon, a squad of about 30 men in civilian clothes and armed with submachine guns arrived in two buses at the fashionable financial-district store of former La Prensa editor Roberto Eisenmann. They fired to disperse a handful of opposition demonstrators waving white handkerchiefs in front of the store, witnesses said. They riddled the display windows with bullets and threw at least a dozen Molotov cocktails inside.

Some of the assailants, decribed by eyewitnesses as supporters of Noriega, stole clothing. They burned an adjacent Jaguar car dealership and at least a dozen cars parked on the block. Private homes in the upper-class neighborhood were riddled with bullets.

Riot police left the area minutes before the attack, witnesses said, and returned when it was over.

The attackers spray-painted "Yankee go home" and "IMF get out of here" on walls. The International Monetary Fund monitors Panama's $4.5 billion foreign debt for this nation of 2.2 million.

President Eric Arturo Delvalle and his wife Maria Diaz appeared briefly at the smoldering store and she told reporters she deplored the attack. Delvalle assumed the presidency after the resignation of Nicolas Ardito Barletta in 1985, allegedly on the orders of Noriega.

Chase Manhattan employes who waved white handkerchiefs outside the bank in a midday protest were pursued by riot police into the bank's offices. Two employes were arrested and several were beaten, other employes said.

Soldiers occupied Radio Mundial, one of only a handful of stations not controlled by Noriega, and the transmitter was dismantled.

In what seemed a restrained move, the opposition National Civic Crusade, made up of business and teachers' groups and clubs including the Lions and Rotarians, called for an hour-a-day work stoppage starting today.

At a rally late yesterday in San Miguelito, a hillside slum, Noriega told followers to reject any parallels between Panama and the fall of Ferdinand Marcos last year in the Philippines.

The confrontation between Noriega and Washington is a culmination of tensions first noted in the early 1980s. Noriega has described the recent protests as part of a U.S. conspiracy to stop Panama from taking control of the Panama Canal by 2000, as mandated by treaties ratified in 1977.

Noriega opened his current anti-U.S. offensive in mid-June, apparently to mobilize his leftist sympathizers and reinforce the loyalty of the defense forces' top commanders.

In May, before the protests, Noriega abruptly cancelled a scheduled meeting in Managua with Nicaraguan Defense Minister Gen. Humberto Ortega, leaving Ortega waiting at the airport, Nicaraguan officials said. Managua indicated that Noriega thus sought not to offend the United States. But last week, Noriega invited Nicaraguan President Daniel Ortega to Panama for a first visit to discuss regional peace issues.

On Saturday, the defense forces' general staff responded to the Senate resolution with an unusual communique accusing the United States of increasing the number of its troops in Panama in violation of the canal treaties.