Woking, Surrey - McLaren has an aggressive programme of development for its car and aims to close the gap to Mercedes by the first European race of the Formula One season in May.
Rookie Kevin Magnussen and Jenson Button finished second and third in the 16 March season-opener in Melbourne that was won comfortably by Mercedes' Nico Rosberg.
Button said Mercedes were about a second a lap quicker than the rest but McLaren racing director Eric Boullier who joined the team this year from Lotus, felt the gap was less.
Boullier said on Wednesday: “It's true that Mercedes and Williams have some pace, maybe between half and three quarters of a second quicker than the rest of the field.
FOCUS ON RELIABILITY
“We focused a lot of our winter on building a solid and reliable car, because we believed - and Australia confirmed our strategy - that reliability was key to taking big points at the beginning of the season.
“Now we’re pushing very aggressively on performance development - we need to clearly catch up the gap to Mercedes and also some others; our target is to catch up by Barcelona and build up over the first few races in Europe.”
The Spanish Grand Prix, fifth of 19 races this season, is on 11 May.
The podium positions in Australia were McLaren's first since 2012 with the team suffering their worst championship in decades last season.
Boullier warned that some other teams that had under-performed in Melbourne would be very fast when they resolved their problems.
Champion Red Bull had Daniel Ricciardo disqualified from second place for exceeding the fuel flow rate while quadruple champion Sebastian Vettel lasted just three laps before retiring.
Red Bull's engine provider Renault had a torrid time in pre-season testing, with Red Bull arriving in Australia without having completed a race simulation.
WORK CUT OUT
Ferrari also recognised it had work to do after Fernando Alonso and Kimi Raikkonen finished fourth and seventh respectively.
Technical director James Allison said: “While we can take some satisfaction from the reliability shown by the F14T, it is clear that we have our work cut out to improve our car in order to compete on equal terms with the Mercedes team.
“We need to work further on the stability under braking and the speed on the straights; we intend to fight our way back up the grid with the improvements that we will bring to the car.”