A man accused of smashing a Muni bus windshield during a riot after the San Francisco Giants' World Series sweep pleaded not guilty Monday, but his attorney said he was ashamed of his actions and hoped to make amends.

Gregory Graniss, 22, was charged last week with felony vandalism after a freelance photographer snapped a picture of him about to ram a police street barricade into the front window of an 8X-Bayshore express bus during the early morning of Oct. 29. Vandals destroyed the $700,000 bus minutes later by setting it on fire.

Photos of the incident were widely circulated through social media.

Graniss was arrested the next day at a San Francisco hotel and was released from jail after posting $40,000 bail, according to authorities.

Graniss, a former high school basketball player from Novato, arrived in court with his parents at his side. He remained quiet during the proceedings, letting his attorney do the talking.

"The San Francisco Giants' victory was amazing, and it really brought out the best in San Francisco and, unfortunately, the worst in Gregory," his attorney, Doug Rappaport, said outside court. Graniss stood next to him holding his mother's hand, his lips trembling. "He is very ashamed of his actions and very, very sorry. And now he's going to set an example by making amends, and he only hopes that San Franciscans will find it in their hearts to forgive him."

Graniss' alleged actions during the Giants riot were also caught on video, and Assistant District Attorney Lindsay Hoopes said the footage may result in more charges being filed against him.

Graniss' face crumpled after Hoopes made that statement in court.

District Attorney George Gascón reiterated his tough stance on the Giants rioters at a news conference after the arraignment and said Graniss will have to face the "consequences of bad behavior, and this is really bad behavior."

"It's nice to hear that he's apologetic," Gascón said. "Unfortunately, we have close to a million dollars in damages. ... We had people on that bus that were placed at risk."

The district attorney's office has received 15 cases so far from the Police Department and filed charges in 12 cases, Gascón said. Police Commander John Murphy said of the more than 30 people arrested during the riot, about 10 were cited and released and about 10 were taken to the station for public intoxication and released the next morning.

Investigators are still looking for many of the Giants riot vandals, including another man caught in a photo smashing the Muni bus and two arsonists caught on video setting fire to it.

Graniss is scheduled to return to court Dec. 17.