BRUSSELS (AP) — European leaders are being guarded in their responses to the deepening tensions between the United States and Iran, urging both sides to step back from confrontation.

Influential European countries have for months been steering a delicate path between Washington and Tehran, since the President Donald Trump's administration last year pulled out of a nuclear agreement with Iran which the European Union is keen to keep intact.

That pact ensures Tehran's nuclear program is restricted to civilian uses in exchange for economic assistance and was signed by Iran, the U.S., Russia, China, France Germany and Britain. It is at risk of collapse due to U.S. sanctions against Iran, leaving Europeans diplomatically hamstrung by the antagonism between Washington and Tehran.

European Council President Donald Tusk said Friday the bloc is urging restraint on both sides in the latest flare-up, after Iran shot down a U.S. surveillance drone. He rejected suggestions that the EU should speak more loudly in the dispute.

"The biggest problems in our history (were) always provoked by too active politics, not too passive," he said at the end of an EU summit in Brussels.

In an indication of the Europeans' uneasiness, the EU summit did not publish a statement on the issue.

German Chancellor Angel Merkel said European countries are still hoping that there can be a political solution.

"Naturally, we are worried about the situation and we're counting on diplomatic negotiations for a political solution to a very tense situation," Merkel said, without elaborating.

The EU's top diplomat is in regular contact with the two capitals, Tusk said.

Moscow also added its voice to the calls for a careful approach.

"The situation in the Persian Gulf is quite tense, and this is a concern for us," Kremlin spokesman Dmitry Peskov told reporters on Friday. "We are following the situation carefully and calling on all countries involved for restraint."