The Argentine coach urged his players to lift themselves up for a final push in La Liga and is baffled at his team's problems in front of goal over the last seven days
Barca's woeful week had already seen them knocked out of the Champions League by Atletico last Wednesday and then all but concede La Liga with a 1-0 loss at Granada on Saturday.
Wednesday's Clasico clash against Madrid at Mestalla therefore represented an opportunity to save something for Martino and Barca in a flagging campaign, but Tata's team were edged out by a late Gareth Bale winner in Valencia and the Argentine coach was left to apologise to the fans who had made the journey to support his side.
"I feel a deep pain for this defeat," he said. "I would like to thank our fans for coming all this way to support us and I apologise to them for not being able to win the match.
Despite a week which has left his team reeling, Martino says Barca will give one final push in La Liga.
"The panorama isn't favourable, but we have to give everything until the end of the season," he said.
Neymar hit the post for Barca late on against Madrid, while Lionel Messi was again unable to hit the target and Marc Bartra's second-half strike was the side's only goal in three games.
"This team is known for scoring lots of goals, but suddenly the goals have dried up," Martino admitted.
"We have had problems in the last 25 metres and that's unusual for this club because normally one of these players produces some brilliance and scores. But we haven't been able to do that this week."
And asked about his own future at the Catalan club, he added: "It has been a tough week, for sure, and we have to find the strength to pick ourselves up.
"Now we're not in good shape, but this team has a big future. I don't think my own future depends on this game or on the last week."