The Australian said he was aware of the stories linking him to other teams, but did not confirm or deny any of the quoted figures attributed to key source Red Bull motorsport advisor Helmut Marko.
The 41st edition of the Dakar will be held from January 6 to 17, 2019, on a loop of ten stages.
The 2018 Belgian Grand Prix will take place on August 24-26.
Red Bull "has reached an agreement with Honda Motor Co Ltd to race with the Japanese manufacturer’s power units for the 2019 and 2020 Formula 1 seasons," it said in a statement.
After seven of the season's 19 races, Lorenzo stands seventh in the overall standings on 66pts, with Marquez atop the pile on 115, followed by Rossi (88) and Maverick Vinales (77).
The 19-year-old started from pole position and beat Portugal's KTM rider Miguel Oliveira by 2.492sec, with Spaniard Alex Marquez of Kalex third at 3.485sec.
Championship leader Marc Marquez was second fastest, with Lorenzo's team-mate Andrea Dovozioso third.
Victory at Le Mans would take Alonso a step closer to the triple crown of racing.
Mercedes expect to introduce their upgraded second engine at the French Grand Prix later this month.
The four-time champion German drove his Ferrari with near flawless aplomb to convert his 54th pole position into a triumph.
The Belgian won the last six stages on Sunday to overturn a 6.8-second deficit and edge Sebastian Ogier.
It is the Italian team's first time on pole in Montreal since seven-time champion Michael Schumacher managed it in 2001.
Belgium's Thierry Neuville was second while Finland's Jari-Matti Latvala was third.
Belgian Thierry Neuville was second Estonia's Ott Tanak was third.
A team spokesman said the new units would be used at the French Grand Prix later in June.