"I don't want to enter an unsafe situation but you see this stuff coming out of France," said the American rider, who has many critics in France. "There're some aggressive, angry emotions. If you believe what you read, my personal safety could be in jeopardy.
"Cycling is a sport of the open road and spectators are lining the road. I try to believe that people, even if they don't like me, will let the race unfold."
Armstrong was asked if he specifically fears a physical attack.
"Yeah. There're directors of French teams that have encouraged people to take to the streets ... elbow to elbow. It's very emotional and tense," he said.
It's unclear why Armstrong is worried about his safety now, given that attacks on riders are extremely rare. Organizers have in recent years taken additional steps to protect riders from spectators, including increased use of crowd barriers.
The Tour has its own police force to guard the route and ensure safety, and French police paid particular attention to Armstrong's safety when he was riding.
Armstrong announced his comeback in September and joined the Astana team. He is reunited with Astana team leader Johanna Bruyneel, who teamed with Armstrong for all seven Tour de France wins from 1999-2005.
Armstrong plans to meet with Tour officials before deciding whether to compete in the 2009 Tour.
Previously, he had expressed doubts over trying for win another Tour title because of the problems he might encounter with French organizers, journalists and fans.
Armstrong is scheduled to race the Giro d'Italia for the first time. The 100th anniversary edition of the Giro is scheduled for May 9-31. The Tour de France starts July 4.
The 37-year-old Armstrong said in the Guardian interview that he is in better shape at this stage of the season than in past years.
"I'm much better physically now," he said at his home in Austin, Texas. "And mentally there is no comparison. I'm far stronger and more motivated. The motivation of 2008 feels like the motivation of 1999. I was back from cancer then. I had the motivation of vengeance because nobody wanted me or believed in me."
Armstrong reiterated his denials of the doping allegations that have dogged him during his career.
"I understand people in France and in cycling might have that perception, but the reality is that there's nothing there," he said. "The level of scrutiny I've had throughout my career from the press and the anti-doping authorities is unmatched. I'm not afraid of anything. I've got nothing to hide. I won seven Tours through hard work.
"This next year won't be any different - even if people hate to hear that. I'm going to be focusing on every aspect of the bike, the team, the strategy, the training, the hard work, the sacrifice. There are no secrets. To the critics, I would say, believe it or not, there are exceptional athletes out there. Michael Phelps ... Paula Radcliffe."
Armstrong also restated his rejection of the French anti-doping agency's proposal that he agree to retest his 1999 urine samples to see whether the French newspaper L'Equipe was right when it reported they contained the banned substance EPO.
"I'm all for drug controls, but if the athlete cannot defend himself, what kind of kangaroo court is that?" he said.