US official says Washington is open for business if Iran wishes to contact them

The United States is "open for business" if Iran wishes to contact Washington, a U.S. official said on Monday, as the United States seeks to pressure Tehran over a government crackdown on protesters.

"I think they know the terms," the official told reporters when asked about the terms of talks with Iran. "They're aware of the terms."

U.S. President Donald Trump said on Thursday that the United States had an "armada" heading toward Iran but hoped he would not have to use it, as he renewed warnings to Tehran against killing protesters or restarting its nuclear program.

Trump had repeatedly threatened to intervene if Iran continued to kill protesters, but the countrywide demonstrations have since abated. The president said he had been told that killings were subsiding and that he believes there is currently no plan for the executions of prisoners.

A U.S. aircraft carrier and supporting warships have arrived in the Middle East, two U.S. officials told Reuters on Monday, expanding Trump's capabilities to defend U.S. forces, or potentially take military action against Iran.

The U.S. military has in the past surged forces into the Middle East at times of heightened tensions, moves that were often defensive.

However, the U.S. military staged a major buildup last year ahead of its June strikes against Iran's nuclear program.

Iran will treat any attack "as an all-out war against us," a senior Iranian official said on Friday.

-Steve Holland and Daphne Psaledakis/Reuters