The EU's trade commissioner says there is "no immediate clarity" from the US on how the bloc can gain exemption from new tariffs on imported steel and aluminium imposed by President Trump.
Cecilia Malmstrom met with the US Trade Representative Robert Lighthizer and Japan's Trade Minister Hiroshige Seko in Brussels.
She said discussions would continue next week.
Mr Seko called for calm-headed behaviour in the dispute.
The EU says that its exports should be excluded from the measures.
Mr Trump's announcement of import tariffs of 25% on steel and 10% on aluminium has sparked fears of a trade war.
The EU has threatened retaliatory tariffs on US goods, including iconic products like bourbon and blue jeans.
Canada and Mexico will be exempt from the tariffs initially, and Australia is optimistic that it too will gain exemption.
Mr Trump has linked this to a new security agreement between the US and Australia, which already have close military ties.
UK Steel says 7% of its steel exports go to the US, worth £360m.
Mr Trump signed the measures on Thursday in a ceremony at the White House attended by steel and aluminium workers.