BERLIN—President Donald Trump is pressing Germany to pull the brakes on a major gas deal with Russia as the price for avoiding a trans-Atlantic trade war, according to German, U.S. and European officials.

The officials said Mr. Trump told German Chancellor Angela Merkel in April that Germany should drop support for Nord Stream 2, an offshore pipeline that would bring gas directly from Russia via the Baltic Sea. This would be in exchange for the U.S. starting talks with the European Union on a new trade deal.

The...