Honda announced its F1 comeback with McLaren last week, but also left the door open to supplying other squads.
"The agreement governing engine supply was actually there to prevent one manufacturer working with too many of the best teams," said Whitmarsh in an interview for this week's episode of The Racer's Edge.
"There is nothing in the regulations to say that an engine manufacturer must supply more than one team, so obviously we are looking forward to an exclusive relationship with Honda."
Although the 2013 F1 sporting regulations match Whitmarsh's believe, the rules for '14 and beyond have not yet been published.
Sir Frank Williams, who may possibly be in the market for Honda engine supply, given his team's long history with the Japanese manufacturer and the high cost of the Renault V6 turbo engine, told F1 Racing that he will be "consulting his lawyers as to the exact position".
WHITMARSH ON KOBAYASHI AND LIVERIES
In the interview, conducted in the McLaren Technology Centre, Whitmarsh also said that a Japanese driver at McLaren "would be nice" but discounted Kamui Kobayashi as a potential candidate.
"If we do look at a Japanese driver," he said, "it would need to be a driver with championship-winning potential. And that, in my view, means a driver who has come up through the established ranks from day one - a driver we can develop."
Whitmarsh also said that a return to McLaren's original orange livery was not impossible and admitted that "knowing when to stop the current development of a car and moving on to the next one" was not one of his strongest suits.
Click here to watch The Racer's Edge. The new episode, featuring Whitmarsh, will be available from 7pm (BST) Wednesday May 22.