Damon, who co-wrote the script and stars in the picture directed by Gus Van Sant, said it was getting harder to make "issue movies" and that he was bewildered by critics who found the story of a natural gas executive wrestling with his conscience implausible and incoherent.
"It didn't get the reception that I would have hoped for but that happens sometimes," he said. "I've had movies bomb worse than this one and then make their money back later."
“Promised Land,” which Damon said cost less than $18 million to make, has only drawn about $7.6 million at the US box office since its late December release, according to trade magazine Variety.
Damon plays a top sales executive working for a company seeking to unlock natural gas from shale rock formations through a process known as hydraulic fracturing or "fracking."
He promises down-on-their-luck Kentucky farmers millions in exchange for their land rights, pitting their immediate economic survival against safety and pollution risks.
Damon, a longtime environmental advocate, said the issues were close to his heart "because the stakes are just so incredibly high and the debate is really raging right now everywhere all over the world."
Yet the Oscar-winning actor's passion did not extend to members of German anti-fracking protest groups who travelled to Berlin in the hope of meeting the star, but whom Damon ignored while greeting fans outside the Berlinale Palast theatre at Potsdamer Platz.
“We didn't think it very nice that Damon walked by us without speaking to us,” said a spokeswoman from a citizens' association which had travelled from near Erfurt to see him.
Fracking has become one of the most divisive environmental issues in the energy sector, particularly in the United States. Since 2007, it has made possible the cost-effective exploitation of immense oil and gas reserves beneath subterranean shale strata, driving down energy prices.
But campaigners argue fracking pollutes the water table and soil with the chemicals it requires and has even triggered earthquakes.
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Germany could use the technique to access enough natural gas to supply the nation for 20 years, Der Spiegel magazine reported in October, but safety concerns have so far caused government authorities to shy away from granting permits to do so.
Energy firms have suggested the film was also marred by a conflict of interest because some of the financing came from the United Arab Emirates, a giant oil exporter for which gas extraction is a major threat.