However the apology cut no ice with many women's groups who would like to see the Hollywood star quit from the race to become California's governor.
The Republican action hero's apology came after allegations emerged that he groped and harassed colleagues and made crude sexual comments. The claims appeared on the front page of The Los Angeles Times.
Schwarzenegger, speaking to supporters in San Diego on Thursday as he kicked off a four-day barnstorming bus tour of the Golden State, acknowledged acting inappropriately.
The Times published interviews with six women who claimed he had harassed them.
“A lot of what you hear in those stories is not true,” Schwarzenegger said. “But as I've always said: 'Where there's smoke, there's fire.”
“(Schwarzenegger) waited until he was outed on the front page of the LA times to apologise”
CODEPINK Women for Peace
“Yes, it is true that I was on rowdy movie sets and I have done things that were not right, that I thought were playful but now I recognise that I have offended people. And those people that I have offended: I want to say I am deeply sorry about that and I apologise.”
His surprising apology came five days before a vote that polls had suggested will usher the former bodybuilder into the California governor's mansion.
Still, women’s advocacy groups gave him no slack and called for simultaneous state-wide protests against him.
“(Schwarzenegger) waited until he was outed on the front page of the LA times to apologise,” Jodie Evans, co-founder of CODEPINK Women for Peace, told AFP.
Most supporters of Schwarzenegger were unfazed by the allegations.
"He has always tried to defuse these accusations"
Prof. Elizabeth Garrett,
University of Southern California
“I know it's true but, you know, men used to do that,” said Beverley Tazelaar who attended the rally with her husband, AFP reported. “Men are all sexual predators. He is a man. I forgive him.”
Political analysts said it was too early to say whether the new allegations would hurt the actor's chances of being elected.
“He has always tried to defuse these accusations,” said University of Southern California political pundit Professor Elizabeth Garrett, who noted that when he announced his candidacy in August, Schwarzenegger warned he would come under attack for alleged “womanising”.