Secretary of State Cyrus R. Vance's exploratory talks have produced encouraging signs that America's major European allies are willing to cooperate in putting economic pressure on Iran, U.S. sources said tonight.

But, a senior state department official travelling with Vance stressed, the discussions are still in an early stage, and there is still uncertainty among all the countries involved about whether such steps would achieve the goal of forcing Iran to free the 50 American hostages in Tehran.

"They were very much interested, but they did not commit themselves," he said. "The Europeans have judgments which don't necessarily differ from ours, but they have to think them through for themselves."

In addition, the official said, further consideration has to be given to the risks involved in putting an economic squeeze on Iran. He noted that, while such a campaign would throw the Iranian economy into chaos, it also could produce serious disruptions in the world trading and monetary systems and cause Iran to fight back by refusing to sell oil to the West.

The official said these are the initial conclusions to emerge from Vance's two days of talks with leaders of major Western industrial countries. He met yesterday with the heads of government in Britain and France, and, following talks in Rome this morning with Italian Prime Minister Francesco Cossiga, Vance flew here tonight for discussions with West German Chancellor Helmut Schmidt.

While stressing that no commitments or agreements have been made yet, the official said that Vance had found "a universal sense of outrage at Iran's flouting of international law" and "strong sympathy and support for the United States" in its efforts to get the hostages freed.

The idea of concerted economic action was triggered by the effects of the measures already instituted against Iran by the United States, particularly the freezing of between $8 billion and $9 billion in Iranian assets held by U.S. banks and their foreign subsidiaries.

It has become apparent that the freeze has had an effect, far greater than originally anticipated, of disrupting Iran's internal economy by making it very difficult for Iran to obtain essential imports, including food grains and cooking oils, military spare parts, equipment for oil fields and manufacturing enterprises and consumer goods.

In addition, the senior official said, the situation is expected to worsen considerably in about six weeks and there are signs that many Iranian leaders, particularly those charged with running the economy, are worried about the situation and would like to find a way out. For that reason, he continued, the Carter Administration has been looking more and more closely at economic pressures and one option would be an informal agreement with the major West European industrial countries to impose an informal trade and financing embargo -- either partial or total -- on Iran.