U.S. law-enforcement officials have expressed fear that last week's kidnaping of a Drug Enforcement Administration agent in Guadalajara, Mexico, may be part of a pattern of increasing assaults on U.S. targets by drug traffickers throughout Latin America.

Agent Enrique Camarena Salazar, 37, a Mexican-born naturalized American with nearly 11 years' experience at the DEA, was abducted in midafternoon last Thursday as he left his office to have lunch with his wife. An eyewitness has told DEA investigators that he was grabbed by four armed men and thrown face down into the back of a car.

U.S. law-enforcement officials said that Camarena, who had a broad working knowledge of DEA operations and continuing investigations in Latin America, may have been tortured and murdered, but they offered no specifics.

The kidnaping was the most recent of several acts of violence by Latin American drug traffickers against U.S. enforcement efforts, which have been sharply increased in the last three years. Law-enforcement officials said they are particularly concerned about the attacks because of violence routinely used by the traffickers, including brutal murders of wives and children of targets. In February 1982, two DEA agents were kidnaped by drug traffickers in Cartagena, Colombia, shot repeatedly and left for dead. Both survived.

Last Oct. 10, a DEA agent's car was machine-gunned in Guadalajara. At that time, DEA security in Mexico was increased, and agents were ordered to be especially vigilant.

On Nov. 26, one woman was killed in a car bombing outside the U.S. Embassy in Bogota, Colombia, that authorities said they believed was carried out by drug traffickers.

Last December, the Colombian government completed plans to extradite four alleged drug traffickers to the United States for trial under a new treaty between the two governments.

About that time, DEA and other intelligence sources received reports that a three-man hit team had been dispatched from Colombia and was targeting federal narcotics agents for kidnaping, torture and murder. The plans also included the possible bombing of DEA offices, the reports said.

Federal law-enforcement sources said that they see no link between the Camarena kidnaping and the alleged Colombian hit squad but that the men who abducted Camarena in Guadalajara are believed to be major traffickers of marijuana and cocaine. The sources said the men are believed to be based in the Guadalajara area but working with drug traffickers elsewhere in Latin America.

Authorities said the situation in Guadalajara is seen as so serious that more than 40 agents are in that area handling the investigation and that DEA Administrator Francis M. (Bud) Mullen Jr. flew to Mexico last Sunday to oversee the operation. He returned last night, but nothing further was announced.

Since December, DEA offices and many other federal buildings, including courthouses, have been under extremely tight security throughout the United States. Intelligence sources said the alleged hit team left Colombia, but federal sources said they do not know whether the team has entered this country.

Federal law-enforcement sources said the team is believed to consist of three men, not drug traffickers but hired by Carlos Lehder, a Colombian citizen wanted on three U.S. drug-trafficking indictments and believed hiding in Colombia.

Lehder has claimed to be a member of M19, a left-wing Colombian terrorist group.

Deputy DEA Administrator John C. Lawn said yesterday, "Acts of violence, threats of violence are a clear indication that the pressure we're bringing to bear on traffickers is having an effect and that they're responding the only way they know how -- by trying to provoke fear and intimidation.

"We have taken precautions in all overseas posts, we have established special working guidelines for our people," he said. "But the nature of our work and the sometimes corrupting environment makes absolute security of personnel impossible. But if traffickers are using fear and intimidation to test our mettle, they're going to find we test well."