That is despite the fact that it has been announced officially that the Spanish driver will contest not only Le Mans, but other WEC sports car races for Toyota this year.
But McLaren executive Brown told the Spanish sports daily AS that Alonso will not miss any grands prix.
“His priority is formula one, so we are open to other racing activities provided that formula one, which is his number 1 priority, is not compromised in any way,” he said.
Alonso missed Monaco for the Indy 500 last year, but the big difference in 2018 is that McLaren is now expecting to field a much more competitive Renault-powered car.
“Everything is going really well with the design of the car,” Brown revealed.
“We just passed the crash test and everything has gone according to plan. We are going to present the car on February 23 and be on track for the first time on February 26.
“All the simulations put us where we wanted to be last year. Sometimes the simulations don’t work when you go to the track, but last year it worked more often than not so I think we’re going to have a solid season,” Brown added.