While partying in Manhattan's trendy Meatpacking District on Saturday, the royal reportedly clashed with former club owner Adam Hock, who was charged with eight counts of third-degree assault for the alleged attacks on the prince and his entourage, the New York Post reports.
"Pierre's face looked broken, with deep cuts and blood everywhere," a witness said after the fight. "He looked like he needed plastic surgery."
Police told PEOPLE, "At 2:22 a.m. Sunday police responded to a call at 63 Gansevoort Street and were met by the complainant, during which he said the defendant punched him in the face."
The alleged brawl broke out at Double Seven when Casiraghi, joined by Stavros Niarchos III (Paris Hilton's ex), Vladimir Restoin Roitfeld and Diego Marroquin, walked up to Hock's table.
"All Hell Broke Loose"The prince, 24, and his pals "were being completely obnoxious" to Hock, 47, and his group, which included Double Seven owner Jeffrey Jah, celebrity hairdresser Joel Warren and models Natasha Poly, Valentina Zelyaeva and Anja Rubik, Hock's group said, according to the Post. They said Casiraghi, grandson of Grace Kelly, and his friends drank from their $500 bottle of vodka and were rude to the models.
"The next thing I saw, all hell broke loose," a witness told the paper. Hock allegedly punched the prince, and he "flew across the room and landed on a table on the other side."
As the models looked on, Hock also allegedly hit Niarchos, 26, Restoin Roitfeld, 27, and Marroquin, 33. Witnesses on both sides said that the royal tried to hit Hock over the head with a bottle of Grey Goose.
"I was defending myself and others," Hock said at his arraignment Sunday in Manhattan Criminal Court. "Why aren't [Casiraghi and his friends] handcuffed?"
And Hock's attorney, Sal Strazullo, tells PEOPLE: "How could my client be accused of attacking four men? These four men attacked my client and his friends at this restaurant/lounge, and in self defense my client defended himself and others, which under law is something he has a right to do."
Officials in Monaco declined to discuss the alleged altercation, telling PEOPLE via a spokesperson on Monday, "We cannot comment right now because we have no information about it."
On Monday afternoon, a spokesperson for the venue, Double Seven, weighed in, telling PEOPLE in a statement, "The facts are very clear. There was only one person arrested Friday night at the Double Seven, Mr. Hock, who spent two days in jail as a result from his actions. We have no further comments."
Hock was released on his own recognizance but is due back in court on March 29, according to the Manhattan district attorney's office, and Casiraghi was released Saturday from New York Presbyterian/Weill Cornell Medical Center.
Reporting by DANA KENNEDY and NICOLE WEISENSEE EGAN