The White House on Monday also said US President George Bush would raise the issue during next week's scheduled meeting with Israeli Prime Minister Ariel Sharon.
"We oppose the expansion of any settlement activity. That has been our view and that remains our view," White House spokesman Scott McClellan said when asked about settlement expansion plans in the West Bank.
"Settlement activity will be a subject that comes up," when Bush and Sharon meet next Monday at the US president's ranch in Crawford, Texas, McClellan said.
The spokesman's comments, however, fell short of the position expressed last month by Secretary of State Condoleezza Rice.
In response to news of Israeli plans to build the homes between Maale Adumim and Arab East Jerusalem, Rice said settlement expansion should come to a "full stop", because it could threaten progress towards peace.
"We oppose the expansion of any settlement activity. That has been our view and that remains our view"
White House spokesman
A senior Bush administration official said Washington's stance had not softened since Rice's statement. The official called the White House's message "direct, clear and unequivocal".
Another official said the Bush administration was putting pressure on Israel largely behind the scenes before the Bush-Sharon meeting.
Rice and Bush's national security adviser, Stephen Hadley, were expected to raise the issue later on Monday in talks with Dov Weissglass, a top Sharon adviser.
Sharon believes an extension of Israel's biggest colony, already home to 30,000 people, is in line with Bush's assurance to him last year that Israel could expect to keep some large settlement blocs under a final peace accord.
"A strip between Jerusalem and Maale Adumim will certainly be built. At what time, under what circumstances, at which phase during negotiations ... I honestly don't know," said Israeli Vice-Prime Minister Ehud Olmert.
Palestinians say the latest project on land Israel occupied in the 1967 Middle East war would cut them off from East Jerusalem, which they want as the capital of their future state.