Under the proposal described to AFP, the EU would commit to ramp up purchases of US liquefied natural gas, along with other investment pledges.
Pharmaceuticals, a key export for Ireland, would also face a 15-percent levy, as would semi-conductors.
The EU also appears to have secured a compromise on steel that could allow a certain quota into the United States before tariffs would apply, the diplomat said.
But Trump said Sunday trade tariffs with the EU would not be lower than 15 percent.
Auto sector
The EU has been hit by multiple waves of tariffs since Trump reclaimed the White House. It is currently subject to a 25 percent levy on cars, 50 percent on steel and aluminium, and an across-the-board tariff of 10 percent, which Washington threatens to hike to 30 percent in a no-deal scenario.
It was unclear how the proposed deal would impact tariff levels on the auto industry, crucial for France and Germany. Carmakers are already reeling from the levies imposed so far.
While 15 percent would be much higher than pre-existing US tariffs on European goods, which average around 4.8 percent, it would mirror the status quo, with companies currently facing an additional flat rate of 10 percent.
