Jon Voight says he and President Donald Trump are working together to save Hollywood ... 'cause the way things are going, he thinks the whole thing could go down the drain -- just like Detroit, Michigan.

The actor gave his first interview to Variety since POTUS announced 100% tariffs on movies made outside the United States ... and he said he wants to keep Hollywood afloat by any means necessary.

Voight says Tinseltown really does need help ... and, it's good news the prez really cares about the film industry -- 'cause that means they can get people to roll up their sleeves and save it.

He adds, "We can’t let it go down the drain like Detroit ... this shouldn’t be political. I don’t know the political identities of the people we’ve talked to. We’ve talked to a lot of people here. I don’t distinguish them on their party affiliation."

Voight says Trump will back a good plan ... 'cause he just wants Hollywood to go back to its Golden Age.

Aside from the stray shot at Detroit, Voight says he feels he and President Trump have both been treated unfairly ... the political fight is over, JV adds -- now is all about coming together and bringing film production back to the States.

People in Hollywood have had mixed reactions to Trump announcing he will enforce a 100% tariff on all foreign-made flicks -- with some, like actor and comedian Adam Carolla, in favor ... while super-producer Charles Wessler says it's an awful idea.