Barack Obama “fundamentally disagrees” with discrimination that targets people based on their religion, a spokesman for the former president has said.
The statement alluded to, but did not specifically mention, President Donald Trump’s temporary ban on refugees from several Muslim-majority countries.
The White House says the ban is not a Muslim ban because dozens of Muslim-majority countries are not affected.
Mr Obama’s spokesman Kevin Lewis says the former president is “heartened” by the amount of engagement being seen across the country.
He is referring to protests against President Trump’s order on immigration and refugees.
Mr Lewis said: “American values are at stake.”
He praised citizens who are exercising constitutional rights to assemble and “have their voices heard”.
Mr Obama has not weighed in on a political issue since leaving office on January 20.
He has said he plans to give Mr Trump room to govern, but would speak out if the president violates basic US values.