European commissioners have criticised Germany for challenging a cap on its industrial CO2 emissions in 2008-12.
Germany issued more CO2 permits than industry needed in 2005
A German minister threatened legal action last month after the commission cut Germany's emission allocation in the EU carbon trading scheme.
Commission chief Jose Manuel Barroso said it would be "unfair" to tailor allocations to countries' wishes.
Environment Commissioner Stavros Dimas said Germany had to put its "nice speeches" into practice.
"If Germany blocks, the rest of Europe doesn't play along. And if Europe doesn't play along, neither does the rest of the world," he said in a weekend interview.
Mr Barroso said the commission had used the same calculation basis for Germany as it had for all the other states, and it would be inappropriate to give one country special treatment.
German Economy Minister Michael Glos threatened legal action in January, following the commission's decision to allow German industry to emit only 453m tonnes of CO2 per year, compared to the 482m tonnes Germany had proposed.
On Monday, Slovenia became only the second country after the UK to have its proposed quota for 2008-12 accepted by the commission, which is determined to create the necessity scarcity of allocations for the plan to work.
ANNUAL CO2 QUOTAS 2008-12
Germany, 453.1m tonnes
The Netherlands, 85.8
Source: European Commission
In 2005 it turned out that the EU had given out more allocations to industry than it needed.
In Germany alone the surplus came to 21m tonnes.
The whole idea of the trading system is to give companies an incentive to produce less CO2, by issuing too few allocations to go round.
A plant that succeeds increasing efficiency can then sell some of its allocations to a plant that has too few.
Eleven of the 13 countries whose 2008-12 quotas have been fixed by the commission so far have been forced to accept cuts to the allocation levels they proposed.
The commission says it will make a decision on France's CO2 plan very soon.
Denmark and Cyprus have yet to submit their plans to the commission, more than seven months after they were due.