Officials from 32 nations were meeting on the sidelines of an annual UN climate conference, with 12 trade ministers in attendance.
The government of Brazil suspects the US-EU measure's real intention is to increase exports from rich countries and is angry that the proposal does not include biofuels.
"The protectionism is like the serpent's head. The serpent will always try put its head up," Amorim said earlier on Sunday.
The US-EU proposal would come into force only as part of an overall agreement in the Doha round of trade talks.
The talks have stalled since they began in Doha, the capital of Qatar, six years ago.
Washington and Brussels targeted 43 goods "with clear environmental benefits," in order to promote their use worldwide in the fight against climate change.
However, earlier this month they rejected a move by Brazil to include biofuels, such as ethanol.
Amorim and Susan Schwab, US trade representative, sparred over how to open markets in environmentally friendly goods and services.
"The only single product whose effects on climate change is already demonstrated - which is ethanol - is not part of the list," said Amorim.
Brazil is the world's leading producer of ethanol.
Ethanol estimate
Amorim said that ethanol use in Brazil had avoided the emission of an estimated 670 million tonnes of carbon dioxide, a gas which warms the Earth's atmosphere, over the past 30 years.
Schwab said that the US adhered to a list of goods and services set by the World Bank, so as not to appear "self-serving".
"The US is a net importer [of the 43 listed elements]. What's complicated about ethanol is it shows up in agricultural negotiations. Part of the confusion is where it shows up technically."
Schwab argued that the US imported $18bn of the goods, while exports came to $15bn.
She said that developing countries including China, Mexico, Malaysia, Taiwan and Indonesia were all top exporters of the goods on the World Bank list.
Pascal Lamy, head of the World Trade Organisation, said developing countries such as Indonesia, Malaysia and Thailand, were leaders in some clean technologies.
He said that they stood to benefit economically from the free trade in environmental goods.