The Woking-based team's poor start to the campaign has already left Jenson Button and Sergio Perez facing an uphill task to keep themselves in the hunt for the championship.
But Whitmarsh is reluctant to abandon the 2013 campaign yet, as McLaren waits to see how much performance it gains from a big upgrade package for the Spanish Grand Prix.
When asked if there was not a temptation to get a head start on 2014 car development, Whitmarsh said: "There might be in the organisation, but that is one of my flaws: I don't want to go racing if we are not competitive.
"Maybe it is a character flaw, but I have made it reasonably clear from Australia that I am not even talking about 2014 at the moment.
"One of my weaknesses is I want to be competitive. I want to get back to the front and I want to come to grands prix thinking we can win.
"We haven't thought that for the last four races and we want to get it back."
Whitmarsh added that McLaren's first focus was to start racing at the front, before thinking about making up ground in the title race.
"The truth is, what I want to see is getting on the podium and getting on the top steps," he said, when asked by AUTOSPORT about his feelings on the championship.
"I am thinking more of that, and that is what we have to do - one step at a time.
"Going racing when you don't think you can win is not something I enjoy particularly, so I want to get back to the point where you are coming in on Thursday with the anticipation that we can win.
"That is how I want us to be and that is how people expect us to be."