Matt Damon defended his new anti-fracking feature, Berlin film festival contender "Promised Land", Friday against poor reviews and ticket sales and said it was getting harder to make "issue movies".
Damon, who co-wrote the script and stars in the picture directed by Gus Van Sant, said 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."
Damon said he was trying nevertheless to take the knocks seriously, warning that having the major major Hollywood clout that he enjoys could be blinding.
"I'm leery of becoming one of those people who lives so much in a bubble, who thinks that everything I do is great," he said after a press screening of the film that drew polite applause.
"But with this one I just really love it and a big part of my heart is in it... and I don't understand what I'm hearing back."
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."
The actor lamented that pulling together financing for movies not targeted at "13-year-old kids" was much tougher than just five years ago.
"It's getting harder and harder to make movies about things," he said, adding that many of his favourite collaborators were seeking refuge in television which is less expensive to produce and seeing a creative renaissance in the US.
Van Sant, who made the 1997 film "Good Will Hunting" for which Damon and his childhood friend Ben Affleck won a screenwriting Oscar, said he was attracted to the script because none of the characters are what they initially seem.
"He is perhaps a perfect combination of hero and non-hero," he said of Damon's salesman.
The movie, 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.
"The authenticity of Van Sant's portraiture has the effect of exposing a certain inauthenticity at the story's core," a Variety critic wrote.
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.
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.
"Promised Land" is one of 19 contenders for the 63rd Berlinale's Golden Bear top prize, to be awarded on February 16.