BRUSSELS — In a decision that could worsen tensions with Tehran, the European Union on Monday removed a prominent Iranian opposition group from its list of banned terror organizations.

The move ended a long legal battle by the People’s Mujahedeen of Iran, which was placed on the list in 2002, and came at a sensitive moment in relations between the E.U. and the government of Iran.

The 27-nation bloc Monday sought to play down the political implications of the move, arguing that it was the result of decisions by the European Court of Justice, the E.U.’s highest court, which had been asked to rule on the inclusion of the group on the list of terror organizations.

“What we are doing today,” said the bloc’s foreign policy chief, Javier Solana, according to The Associated Press “is abiding by the interpretations of the European court. There’s nothing we can do about this.”

The government in Tehran had made it clear that it opposed any change to the standing of an opposition group that advocates the overthrow of the Iranian leadership.

The decision came as the E.U. awaited fresh moves from President Barack Obama, who is expected to consider direct negotiations with Iran to try to resolve the impasse over its nuclear ambition.

In his inaugural address, Mr. Obama said his government would “extend a hand” to any foe willing to unclench its fist.

Maryam Rajavi, president-elect of the National Council of Resistance of Iran, said in a statement that removing the organization was “a crushing defeat to Europe’s policy of appeasement.”

The E.U.’s list of banned organizations also includes Hamas, although there is pressure from some European nations to review its status.