The pair made contact during a mid-race squabble, with the Lotus driver running Button out of road on the run into the Turn 6/7 chicane.
While both cars were able to continue, Button said afterwards that the outcome could have been a lot worse, and that there was nothing he could do to avoid contact.
The stewards are currently investigating the incident.
"I'm going to see the stewards about it, but I think it's pretty straightforward - I couldn't go any more left," said the McLaren driver.
"That's it, really. Unless I'm on the grass, which is not where I want to be when I'm braking for a corner, he had no way of not hitting me. I obviously didn't realise how narrow the circuit was at that corner...
"It could have been a lot worse than it was. It could have ended both of our races. I was quite lucky. I think our cars are robust."
Button added that he could see the incident happening, but was powerless to stop it.
"I was there, basically with my arm out the cockpit, going 'what are you doing? I'm going to be on the grass in a second.' And I was.
"I don't know what he was thinking. I don't think he was thinking at that point."