The agency used the lighthearted joke as a segue into some more serious bear safety tips.
"Seeing a bear in the wild is a special treat for any visitor to a national park," the agency wrote in another tweet. "While it is an exciting moment, it is important to remember that bears in national parks are wild and can be dangerous."
The service points out that as spring approaches, bears will become more active. On their website, the National Park Service advises visitors who encounter a bear to keep their distance from the animal and to not surprise the bear if it hasn't noticed you yet. If the bear notices you, you should "identify yourself" as a human by standing still, talking calmly and waving your arms. Hikers should also travel in groups if possible.
The website also notes that bear attacks are rare but can occur.
A bear attacked a mountain climber on the side of a cliff and the harrowing exchange was caught on camera. HLN's Robin Meade has the details.
On Twitter, users seemed more interested in soliciting further friendship advice from the National Park Service than learning more about bear safety.
One user, for instance, asked what they should do "if they consider me a friend, but I just consider them an acquaintance."
"Friendships are special, but they don't happen by chance," the agency replied. "It takes effort and trust to build a lasting friendship. Good luck."
A Colorado bear bares all in 400 bear "selfies." CNN's Jeanne Moos explains how it strikes a pose.