The ships entered waters adjacent to Gaven and Chigua reefs in the Spratly Islands, which Beijing calls Nansha, on May 6, China's foreign ministry said.
The US will however ensure that communications with Beijing remain open to prevent any untoward incidents, he added.
"I really value the channel of communication that I have with Shen Jinlong," he told reporters, referring to his Chinese counterpart.
"We just recently visited China, we had a chance to get to know each other, understand each other more thoroughly.
"We can continue to advocate that while we may not see things the same in all parts of the world, we've got to work through those differences in a way that doesn't boil over into conflict." The US Navy regularly conducts freedom of navigation operations to challenge Beijing's vast claims in the sea, often angering China.
After last week's sail-by, a foreign ministry spokesman said "the Chinese side expresses strong dissatisfaction and resolute opposition" to the US action.
But Richardson insisted the patrols were routine.
"We haven't done anything increasingly provocative or anything else that we would not do anywhere else in the world," he said.
Beijing has built artificial islands and military installations in the South China Sea, including on the Spratlys.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)