The Blaugrana fell 1-0 down in the first instalment of the last-eight tie, but recovered to run out 4-1 winners and put one foot in the semi-finals, though the Argentine says their place in the next round is far from guaranteed.
“These are the games that worry me,” the 51-year-old told reporters. “I always have the feeling that the match is thought to be all over when actually you have another 90 minutes ahead.
“The match against Levante deserves all of our concentration as we cannot let our opponent get back in the tie."
Martino is also hoping that his team will make headlines for their on-field performances after the continued controversy surrounding the summer signing of Neymar ended with the resignation of president Sandro Rosell last week.
"The people of Barcelona are still supporting us in the same manner as they have done in recent years. At the moment the team is playing well and people will come to support us because we are playing at a high level and can offer a good show.
“Hopefully, our good performances can get everybody talking only about football [and not about behind-the-scenes situations].
“These players have experienced in recent years very serious difficulties, this situation has also been difficult," admitted the Barca coach.