Germany, France, and Great Britain have urged Tehran to stick by the terms of the 2015 deal that restricted Iran's nuclear program in exchange for sanctions relief.
In a joint statement on January 12, German Chancellor Angela Merkel, French President Emmanuel Macron, and British Prime Minister Boris Johnson said that "it is essential that Iran return to full compliance with its commitment under the agreement."
Iran said last week that it no longer considered itself bound by the agreement, from which the United States withdrew in 2018.
U.S. President Donald Trump called the deal "fatally flawed," in part because it did not restrict Tehran's ballistic-missile program or address its support for terrorist groups in the Middle East.
Last week, Trump urged European countries to also renounce the deal.
The January 12 joint statement noted that "we must address -- through diplomacy and in a meaningful way -- shared concerns about Iran's destabilizing regional activities, including those linked to its missile program."
U.S. Defense Secretary Mark Esper said on U.S. television on January 12 that the administration was prepared to open talks with Iran "without precondition" to work out "a series of steps by which Iran becomes a more normal country."
"The president has drawn no preconditions other than to say we're willing to meet with the Iranian government," Esper said.