WASHINGTON - President Barack Obama said Tuesday that foreign firms testing commercial prospects in Iran did so at their own peril and vowed to come down like a “ton of bricks” on sanctions violators.

Obama spoke alongside French President Francois Hollande a week after a large French business delegation traveled to Tehran to test opportunities that could be opened by the easing of Western sanctions.

“Businesses may be exploring – are there some possibilities to get in sooner rather than later if and when there is an actual agreement to be had?” Obama said.

“But I can tell you that they do so at their own peril right now. Because we will come down on them like a ton of bricks.”

Hollande, meanwhile, said that he did not control French corporations but had made clear sanctions on Iran would not be dismantled until a final deal on Iran’s nuclear program had been reached.

“Sanctions will only be lifted if and when there is definite agreement,” Hollande said.

“During this period of the interim agreement, they remain in force.”

The 116-strong French delegation, with representatives from major companies like Total, Lafarge and Peugeot, was the largest of its kind from Europe since a landmark nuclear deal reached with the major powers in November gave Iran limited relief from crippling US and EU sanctions.

Meanwhile, the Pentagon has said it was unconcerned by an Iranian announcement that it would send naval vessels toward US maritime borders, noting that lots of countries operated in international waters in the Atlantic.

An Iranian naval officer was quoted by the semi-official Fars news agency as saying on Saturday that the vessels were “approaching the United States’ maritime borders.”

The Pentagon has no information the ships are approaching the Atlantic yet, spokesman Colonel Steve Warren said, adding that “to our knowledge, this is an announcement only at this point.”

“We are not concerned about their announcement to send ships into the Atlantic. As I said earlier, freedom of the seas applies to every nation,” Warren said.

He said if Iranian ships do head into the Atlantic, “they should not be surprised to find many other navies also sailing in the Atlantic.”

Fars said the plan was part of “Iran’s response to Washington’s beefed up naval presence in the Persian Gulf.”

The United States and its allies regularly stage naval exercises in the Gulf, saying they want to ensure freedom of navigation in the waterway through which 40 percent of the world’s seaborne oil exports passes. US military facilities in the region include a base for its Fifth Fleet in the Gulf Arab kingdom of Bahrain.

Iran sees the Gulf as its own backyard and believes it has a legitimate interest in expanding its influence there. Iranian officials have often said Iran could block the Strait of Hormuz, at the mouth of the Gulf, if it came under military attack over its disputed nuclear program, and the Western war games are seen in the region as an attempt to deter any such move.