England trail 2-0 in the five-test series after being outplayed with bat, ball and in the field during the eight-wicket loss in the day-night match in Brisbane.
"We weren't able to execute with bat and ball and will be having some conversations in the dressing room," Stokes said.
"In small passages, we have been able to bring the game back into some kind of control and then let it slip away.
"I think a lot of it, to me, comes down to not being able to stand up to the pressure of this format.
"It seems to be a constant that when the pressure is on, Australia keep outdoing us."
The tourists showed flashes of individual brilliance with Joe Root scoring his first Ashes century in Australia. Stokes and Will Jacks combined for a fighting 96-run stand on day four.
But England were chasing the game from day two after their bowlers were powerless to stop the hosts racking up a first innings total of 511 in reply to the tourists' 334.
Only one team in the history of Ashes cricket has ever overcome a 2-0 deficit to win a series - Don Bradman's Australia in 1936-37.
However, Stokes said he had absolute faith in his players and staff to win the remaining tests in Adelaide, Melbourne and Sydney.
"They say Australia is not a place for weak men, and we are definitely not weak but we need to find something," he said.
"We won't shy away from the battle but we need to sort things out pretty quick if we want to bring the Ashes back to England."
The third test starts in Adelaide on December 17th.