Grounded: The musicians were escorted from the plane
Some 100 members of the St Petersburg Philharmonic were removed from the plane in Washington on Monday during a routine stop in an Amsterdam to Los Angeles flight.
The musicians had to spend the night in Washington and continue their journey the following day.
In a statement, the orchestra apologised to the pilot, the crew and the passengers for "our unpardonable conduct".
The statement was obtained by the New York office of the Russian news agency Itar-Tass.
"They were causing quite a disturbance to other passengers on the flight through their rowdiness and inebriation," an airline spokeswoman said.
"Though there were repeated attempts to get them to temper their behaviour, they repeatedly refused to obey instructions from the crew."
The musicians were removed from the flight because it was felt they could not be relied upon to curb their behaviour, she said.
They had continued their journey with United the following day without incident, the intervening 24 hours having "brought a lot of clarity for them", the spokeswoman added.
"This is the sort of thing you expect from a heavy metal band, not a philharmonic orchestra, another United official said.
Monday's problems on flight 947 reportedly began after orchestra members produced bottles had carried on board with them.
They were at the beginning a month-long tour of the US - the orchestra's first since 1998.
Known for years as the Leningrad Philharmonic, the St Petersburg orchestra traces its roots to 1882.