THIS SUMMER, in the 13th year of Gen. Augusto Pinochet's military dictatorship, political resistance is rising in Chile. The general's troops have responded savagely. During a protest strike at the beginning of this month, soldiers in Santiago shot and killed three people, including a 13-year-old girl. Two students in their late teens were beaten and, according to witnesses, deliberately burned by an army patrol. One of them, Rodrigo Rojas de Negri, a resident of Washington who had graduated from high school here, died of his injuries four days later. In a further act of indecency, Gen. Pinochet's security forces gassed the mourners at the funeral. Sen. Jesse Helms (R-N.C.) promptly paid a friendly call on Gen. Pinochet and, at a press conference, declared that the news reports of the spreading violence were presenting a very unfair and distorted picture of the country and the fine people who are running it.

The Reagan administration, recognizing that the stability of Chile hinges on its expeditious return to its democratic roots, has taken an approach refreshingly different from that of the senator. It has publicly called on the Pinochet regime to identify and prosecute those responsible for the bloodshed during the strike. Its ambassador, Harry Barnes, and officials in Washington have repeatedly asked for an independent investigation of Mr. Rojas' death -- an investigation that will not be necessary, the regime's volunteer apologist, Sen. Helms, told his press conference, since the Chilean government is carrying out its own. President Reagan, further, has rebuffed the senator's crude efforts to induce him to disavow his ambassador.

"The United States ought to understand that Chile is one of two countries in the entire Latin American area that resists communism," said the senator at his press conference. The other? Paraguay. Those governments are, in fact, the two conspicuous exceptions to the revival of democratic government that has been sweeping across South America. But when Sen. Helms looks at an anti-democratic government ruling by the gun, he sees only anticommunism. Chile's transition to democracy, he continued, "is on an orderly course." But only by his standards. On the day the senator spoke, Gen. Pinochet indicated that when his present eight-year term ends in 1989 he will remain in office for another -- unelected -- term ending in 1997. He is neither making a transition to democracy nor assuring order.

Still, there is a bright side to Mr. Helms's outrageous intervention. It has prompted the Reagan administration to rebut him vigorously -- no small political event -- and to make a bold and useful assertion of the American interest in the progress of democracy in Chile.