Boro have won just one game back in the top flight so far this season and sit just outside the relegation zone on goal difference following the 1-0 defeat against Watford on Saturday.
Karanka's men have struggled to make the step up to the Premier League so far and Karanka admits the campaign has not begun well - but he's backing his players to get things right soon.
"I know that this isn't a nice moment for everybody," Karanka said in the Gazette. "But we're in the Premier League, we're in October, so we have to be positive.
"We have to recover physically and mentally. We have a good group of players, a strong group of players, so we have to keep going.
"Of course, I am positive. If we can't believe in ourselves then who can believe in us?"
Boro are back in action on Saturday when they go to in-form Arsenal.