State Department spokeswoman Jen Psaki said Washington was "deeply concerned" by the reports and American embassy officials were having high-level talks with Israeli leaders to seek more information.
"We continue to make our position absolutely clear that we view settlement activity as illegitimate and unequivocally oppose unilateral steps that prejudge the future of Jerusalem," Psaki told reporters.
"Israel's leaders have said they would support a pathway to a two-state solution, but moving forward with this type of action would be incompatible with the pursuit of peace," she added.
But the US fails to back its words with any threatened consequences against Israel, and remains the country's staunchest ally.
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"Ties between us are unshakable," Psaki reiterated.
"There are times when we disagree with actions of the Israeli government, including... The issue of settlements, where we have deep concerns about some of the steps the government is taking," she said.
"We expressed those, but it does not mean that we don't have a strong and formidable relationship that continues."