Media reports said former Formula One supremo Bernie Ecclestone, who was in Monaco and has an extensive collection of race cars, had bought it but he told Reuters by telephone that was not the case.
The McLaren was the last Formula One car raced around the street circuit by the triple champion, who died at Italy's Imola circuit in a Williams in May 1994, and took Senna to his record sixth win in the principality.
Bonhams said the fully-functional car, with the original V8 engine and gearbox, was the most historically important Formula One McLaren had ever presented at auction.
Senna's first Monaco car, a 1984 Toleman-Hart TG184, also sold at the 'Les Grandes Marques a Monaco' auction for 1.6 million euros.
(Reporting by Alan Baldwin, editing by Ken Ferris)
