The European Union would consider limiting its new aviation carbon levy to its own airspace, but only as part of a global deal on plane emissions, a senior commission official said.
But he said such a scheme would be technically difficult and was unlikely before a US presidential election in November.
A new law to charge a carbon levy on flights in and out of the European Union officially took effect on January 1, prompting warnings from governments, airlines and plane makers that it could lead to chaos in the skies and a trade war.
Nations such as China, India and the United States are unhappy that the EU went ahead with a scheme that applies to their airspace, while the EU says it was forced to act after years of international inaction on air travel pollution.
The EU has said the only reason it would alter course would be if the United Nations' International Civil Aviation Organization (ICAO) could come up with a global plan to tackle rising carbon emissions from the sector.
The EU levy charges for the entire length of an journey of an aircraft flying into the European union, including the section outside EU airspace.
The commission is willing to consider an alternative scheme that would just charge for the air miles over European airspace, European Commission director general for climate action Jos Delbeke, told reporters after giving a speech in Dublin.
"If ICAO could work it out, we are ready to look at that," he said. "But that is not easily done. ICAO said that an airspace approach is highly complicated."
Any ICAO deal may be delayed until after the US election in November due to the political sensitivity of the issue among voters, he said.
"We observe the reticence that our American colleagues are showing to go into an open debate," Delbeke said.
"We hope that if not shortly before, then immediately after the US elections we would have a solution on the table," he said.