The Swiss Competition Commission (COMCO) said it received complaints in the latter half of 2010 from nationals who unsuccessfully tried to buy its BMW and Mini cars in the European Economic Area (EEA) due to a clause in the contract of dealers operating there.
The clause banned sales to clients outside the EEA, hindering parallel imports to Switzerland by individuals, it said.
During this period the Swiss franc had risen considerably against the euro, COMCO said, which made buying products in the eurozone more attractive.
"Buyers in Switzerland were not able to profit from the significant exchange rate savings," said COMCO.
"BMW closed off the Swiss market by banning its dealers in the EEA from selling new BMW and Mini vehicles to Swiss clients," the authority said, adding that the clause should be deleted.
The car giant said it "categorically rejected" the charge and will file an appeal against the fine with the Swiss Federal Administrative Court.
"The Swiss automobile market was not foreclosed by BMW AG, as proven by the fact that its direct imports to Switzerland are comparable with those of other manufacturers," the company said in a statement.
"The provisions of the BMW and MINI dealer agreements for the EEA have not had any impact on competition in Switzerland."
Comco launched its inquiry into BMW in October 2010.