"He's happiest being a single guy right now - for the foreseeable future."
Last week McConaughey and close friend Lance Armstrong spoke out to deny rumours that they are gay.
The pair - who have been photographed together shirtless on several occasions - have laughed off rumors their friendship has turned physical.
Matthew joked: "We tried it. It wasn't for us!"
The actor then added: "A lot of people don't understand friendship and brotherhood. I have a great friend in him. I'd do anything he asked me to, even though he'd probably never ask me to, and he feels the same way."
Seven-time Tour de France cycling champion Lance - who called off his engagement to singer Sheryl Crow earlier this year - admits he and Matthew had no idea their relationship would become so strong.
He explained: "Our friendship just developed. He got out of a relationship and I'd just gotten out of a relationship.
"I think people see pictures and they think we're these overgrown frat guys, but we all have those kinds of relationships - and relationship isn't a bad word."