The Portuguese side face the Gunners for the second leg at the Emirates after having won the first leg 2-1.
Meireles said: “We will not be ultra-defensive in London. That’s not our style and to try to play that way would be a disaster for us.
“Arsenal are a dangerous team in attack and to give them the ball would cause chaos for us.
“The big battle will be in midfield. We must stop Cesc Fabregas but also the other men in that area.
“I’m optimistic and our squad have the confidence and belief that we will reach the last eight.”