Arms control talks with the Soviet Union "are never going to get anywhere" until they return to the private diplomacy that led up to the Geneva summit last November, Secretary of State George P. Shultz said today.

Heading for home after a 10-day swing through Western Europe, Shultz told reporters traveling with him en route to a refueling stop here that the Soviets were to blame for the current trend of arms control initiatives through press releases.

Shultz made the point one day after Soviet leader Mikhail Gorbachev called publicly for President Reagan to meet him in Europe to negotiate a nuclear test ban.

"If we're going to see a return to the kind of progress we were making in the period before the Geneva meeting," Shultz said. "We're going to have to be settling into some conversations that are direct between the Soviets and ourselves."

"There's a pattern now that they started" by announcing recent test-ban proposals publicly before making them privately, Shultz said. "We are never going to get anywhere doing things that way."

As for the U.S. side's public diplomacy, Shultz recalled that when he gave Soviet Premier Nikolai Ryzhkov a letter from Reagan two weeks ago at the funeral of Swedish Prime Minister Olof Palme, the content of the letter had already been given to the press and responded to in Tass, the Soviet news service.

The letter, responding to the Soviet proposal to join a unilateral nuclear testing moratorium, invited Gorbachev to send witnesses to an underground nuclear test in the United States. The State Department briefed reporters on it the day before Shultz met Ryzhkov.

Reagan again rejected Gorbachev's renewed call for a halt in testing yesterday and repeated an invitation for Gorbachev to set a date to visit the United States.

Shultz said he would stress his call for private talks in order to move forward. "I'm not saying there isn't a public diplomacy aspect to this relationship all the time, but there's got to be more than that . . . "

Shultz said he "felt very good" about his visits to France, Turkey, Greece and Italy, which were dominated by reaction to U.S. military moves against Libyan leader Muammar Qaddafi. "Everybody seems to agree Qaddafi is a problem," Shultz said. "The only disagreement is about what is the right tactic to handle him."

Shultz got lukewarm support at best for the Gulf of Sidra operation from his hosts on this trip, but he said he thought "people are moving in the direction of more action." He said he had been "trying to persuade people" that terrorism must be confronted "in a much more direct way."

Shultz dismissed a suggestion from Italian Foreign Minister Giulio Andreotti that the Libya dispute should have been taken to the International Court of Justice in The Hague. "I don't see any point in that," he said. "We don't want to get into the position where every time some terrorist decides he's going to claim something we go running off to the World Court." Later, Shultz said legal justification for the U.S. action was "unassailable."

Before leaving Rome, Shultz and his party attended an Easter mass at St. Peter's Basilica, where they were honored with seats just a few feet from the outdoor altar. Shultz's wife, Helena, a Roman Catholic, received communion from Pope John Paul II.

Afterward, Shultz met with the pope for the second time during this trip. The talks last night and this morning "were entirely substantive, right from the first word," Shultz said, but he declined to reveal the content.

Shultz said he had delivered a message from Reagan to the pope and had received one in return to take back to the president.

"We had a very good exchange," Shultz said. "He's a very powerful personality to meet with. He engages you right up close, . . . and the rest of the world might as well not be there."