The EU law in question is one of more than a dozen policies designed to reduce the bloc's net emissions by 55% by 2030 from 1990 levels.
That is one of the most ambitious climate targets of any major economy, but the campaigners want it lifted to 65%.
The European Commission is examining the request, a spokesperson said.
"The Commission does not consider this implementing decision to be in breach of fundamental rights," the spokesperson added, referring to the EU law.
All EU countries have approved the collective 55% emissions target, which is fixed into law.
Persons:
Andreas Linsbauer, Andrea Millhaeusler, Arnd, Romain Didi, Didi, Kate Abnett, William Maclean, Devika
Organizations:
REUTERS, Rights, Environmental, European Commission, Union, EU, Reuters, European, Thomson
Locations:
Pontresina, Switzerland, Europe, Brussels, EU, Paris