But the Woking based team's boss did not deny McLaren designers are working on the straightline-speed boosting concept.
"We are not announcing when, where and if we are going to be introducing it," he told reporters during sponsor Vodafone's regular media teleconference.
"I think we will see different wing variants, certainly on our car along with a number of visual items as they go through scrutineering later today and hit the track on Friday.
"We will see new bits, but McLaren will not have a double DRS in Belgium," Whitmarsh said from Belgium.
He also refused to rule out a scenario where Jenson Button, who is 41 points behind teammate Lewis Hamilton's points tally with nine races to go, might eventually fall in line to support the sister McLaren's title charge.
But "It will be quite a few races before we make that decision," Whitmarsh – who insisted McLaren's long-standing policy of driver equality remained in place – said.
"There may well come a point (when team orders are used), but there are still many races left and many points on offer — things can change quickly."
08/28/12 (GMM) McLaren may also be preparing a 'double DRS'-like system for this weekend's Belgian grand prix.
We reported early this month that the British team looked set to follow Mercedes and Lotus' lead in developing an iteration of the straight-line speed-boosting concept.
"It's not like the Lotus one, but we are studying such a system," McLaren's sporting director Sam Michael was quoted as saying.
Mercedes debuted the concept early this season, and after practicing with a similar system at recent races, Lotus' technical boss James Allison revealed this week that the black and gold E20 could race its "device" for the first time at Spa.
And Brazilian correspondent Livio Oricchio now reports that, while the news is much quieter than Lotus', McLaren has similar plans to run a double-DRS at the high speed Belgian track.
The O Estado de S.Paulo journalist said it is not clear how McLaren's system differs to those fielded by Mercedes and Lotus.
After a recent performance dip, Lewis Hamilton entered the August break as F1's last-start winner, having secured his second victory of the 2012 season in Hungary.
"I think it's still difficult to predict accurately who'll win the next grand prix, but I reckon the coming few weeks ought to give us a much clearer idea of the destination of the world title," the McLaren driver said last Friday.
"There's no team with a clear advantage, although we're all pushing hard to catch Fernando (Alonso) in the drivers' championship, so there's still everything to play for," he added.