The White House has vowed to overturn an "outrageous" court block on its travel ban.
US President Donald Trump's executive order bars nationals from seven countries entering the United States.
However, a federal judge in Seattle on Friday (local time) granted a nationwide temporary restraining order blocking the order.
Now, the White House says it will appeal.
"At the earliest possible time, the Department of Justice intends to file an emergency stay of this outrageous order and defend the executive order of the President, which we believe is lawful and appropriate," a White House press secretary said.
"The President's order is intended to protect the homeland and he has the constitutional authority and responsibility to protect the American people."
The court challenge against Mr Trump's executive order was brought by the state of Washington and later joined by the state of Minnesota.
The Seattle judge ruled that the states have legal standing to sue, which could help Democratic attorneys-general take on Trump in court on issues beyond immigration.
The decision came on a day that attorneys from four states were in courts challenging the executive order.
Trump's administration justified the action on national security grounds, but opponents labelled it an unconstitutional order targeting people based on religious beliefs.
Earlier on Friday, a federal judge in Boston declined to extend a temporary restraining order that allowed some immigrants into the United States from certain countries despite being barred by US President Donald Trump's recent executive order.
Also on Friday in Virginia, a federal judge ordered the White House to provide a list of all people stopped from entering the United States by the travel ban.