The Court of Arbitration for Sport ruled that the 31-year-old had breached his contract when leaving the Russian club in 2014.
Diarra, now with Marseille, left Lokomotiv after having his salary cut.
"I will accept the situation as I have always done," said the former Chelsea, Arsenal and Portsmouth player.
Diarra, who won the FA Cup in 2007 with Chelsea and then with Portsmouth a year later, was named in France's final 23-man squad for Euro 2016 on Saturday.
Having left Lokomotiv after a year with the club, Diarra was banned for 15 months before signing for Marseille in the summer of 2015.
"It boils down to a 15 month-match suspension (already served), a 15-month-salary suspension (already served), 110,000 euros for the benefit of CAS and a 10 million euro fine," he added on his Twitter account.
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France midfielder Lassana Diarra has been ordered to pay a fine of 10m euros (£7.6m) to his former club Lokomotiv Moscow.