GENEVA, AUG. 7 -- Soviet Foreign Minister Eduard Shevardnadze and chief U.S. arms negotiator Max Kampelman agreed today to intensify talks on a proposed intermediate-range nuclear missile treaty in coming weeks in hope of laying the groundwork for a successful meeting between Shevardnadze and Secretary of State George P. Shultz in mid-September, both officials said.

Shevardnadze suggested that his three-hour meeting with Kampelman had yielded some "nuances" that pointed to ways to resolve the major dispute over whether U.S.-controlled warheads on 72 West German-owned Pershing IA missiles should be destroyed as part of the deal.

But Shevardnadze also accused the United States of holding up a treaty on intermediate-range missiles and singled out the U.S. negotiating team at Geneva for what he called "somewhat disappointing" behavior.

The Shultz-Shevardnadze meeting, scheduled in Washington Sept. 15-17, is aimed at achieving enough progress on arms control issues to make possible a summit between President Reagan and Soviet leader Mikhail Gorbachev later this year.

The two superpowers are closest to agreeing on a treaty to dismantle all of their intermediate-range missiles and warheads with ranges of 300 to 3,500 miles. They still are at odds, however, over how to handle the Pershing IAs, which have a range of 460 miles but are under joint U.S.-West German control.

Asked at a news conference whether Kampelman had softened his position on the Pershing IAs, Shevardnadze said, "There are some nuances, and they will be subject to negotiation." He declined to discuss what he called the "secrets of my conversation with Mr. Kampelman."

Kampelman said at a later news conference that he was "not at all clear" about what nuances Shevardnadze was referring to.

Kampelman repeatedly reaffirmed the U.S. position that the Pershing IAs are outside the scope of the bilateral, U.S.-Soviet treaty being discussed at Geneva because they are part of a U.S.-West German cooperation program. But John Woodworth, the No. 2 U.S. negotiator for intermediate-range missiles, said that it was "impossible" to say what might happen to the Pershing IAs outside the Geneva talks.

The Soviets want the Pershing IA warheads destroyed as a condition for signing the proposed treaty.

Shevardnadze said that he and Kampelman had agreed that there was "some substantial potential for better preparing a foreign ministers' meeting and for some good movement on some questions, particularly related to intermediate-range . . . missiles."

Shevardnadze also said that he and Kampelman had agreed that the two delegations would use the time between now and the Shultz-Shevardnadze meeting "to prepare a mutually acceptable draft agreement" on intermediate-range missiles.

The U.S. delegation denied that it had agreed to come up with a completed draft treaty by then. Kampelman said that the Americans would not negotiate under time pressure, and Woodworth expressed doubt that the two sides could agree on all details of a draft treaty in such a short time.

Woodworth said that the remaining issues were "mainly of a technical character." But the differences require "time and meticulous work" before agreement can be reached on legally binding treaty language, he said.

The two delegations here already are working with a single draft of the proposed treaty. The remaining differences are denoted by brackets, which indicate the contrasting language proposed by each side.

Kampelman rejected Shevardnadze's charge that the United States was blocking an accord. He joked that the Soviet minister was "a charter member of a new organization: Blame America Only."

Kampelman added, "We both agreed on the importance of expediting movement on these negotiations."

Regarding the Pershing IAs, Shevardnadze rebuffed a recent West German suggestion that they might be traded for reductions in the Soviets' arsenal of battlefield-range Scud missiles.

The Scuds are "a separate issue and a separate subject for negotiations," Shevardnadze said. He visited Geneva for two days to make an address yesterday at the 40-nation Conference on Disarmament.

In that speech he strongly criticized the U.S.-West German position on the Pershing IAs, saying that the two countries were relying on a "legal sham" to avoid destroying the warheads.