Gigi Becali, whose club has played in the group phase of the Champions League competition for the last two seasons, has denied any wrongdoing and appealed the decision.
Police said they were called to a scuffle in the early hours of January 27 when witnesses saw a group of people shove three people into the trunk of a car after blocking traffic.
"We were also told that the aggressors were using guns," Christian Ciocan, Bucharest police spokesman, told Reuters.
The three were taken to a house on the outskirts of the capital Bucharest where they were detained for three hours and accused of taking a black Mercedes owned by Becali, Ciocan said.
"Inquiries will continue until prosecutors decide whether to indict him," the police spokesman said.
The daily newspaper Jurnalul National quoted Becali as saying he was the real victim and that if he had gone to the police to report his missing car he would not have got it back.
"I caught the criminals and they complained to the police. I am accused of deprivation of freedom because my bodyguards recovered the car and took the thieves to a bar," the newspaper quoted him as saying.
Becali also faces trial on charges of offering 1.7 million euros to another soccer club for trying to stop rivals of Steaua, European Cup champions in 1986, from winning the national championship. He denies any wrongdoing.
