(Recasts with defense minister)
MADRID, May 14 (Reuters) - Spain has withdrawn a frigate from a U.S.-led naval group in the Gulf because it was now focusing on alleged threats from Iran rather than an agreed objective to mark an historic seafaring anniversary, the Spanish government said on Tuesday.
"The U.S. government has taken a decision outside of the framework of what had been agreed with the Spanish Navy," acting Defence Minister Margarita Robles told reporters in Brussels.
That led to the temporary pullout of the 215-sailor Mendez Nunez from the group led by aircraft carrier USS Abraham Lincoln as the mission no longer had the objective of celebrating 500 years since the first circumnavigation of the world, as envisaged by a bilateral U.S.-Spanish agreement, she said.
Robles said Spain respected the U.S. decision to focus on Iran and would rejoin the group as soon as it returns to its original task, adding: "Spain will always act as a serious and reliable partner as part of the European Union and within NATO."
While the European Union shares some U.S. concerns about Iran, including its involvement in Syria's war, it still backs a 2015 international nuclear deal with Tehran from which U.S. President Donald Trump withdrew a year ago.
Trump, now trying to isolate Iran, has reimposed sanctions on it and sent the aircraft carrier and B-52 bombers to the Middle East in a move Washington said aimed to offset threats from Iran to American forces in the region.
Trump is also seeking to cut off Iran's oil exports to pressure the Islamic Republic to renegotiate stricter limits on its nuclear program and drop support for proxy forces in Syria, Iraq, Lebanon and Yemen. (Reporting by Paul Day and Jesus Aguado Editing by Mark Heinrich)