Why When i share & click in Facebook i get this message?. Security Alert: This Link May Not Be Safe?

Facebook shows that warning because it thinks the link might lead to a sketchy or harmful site. It could be flagged for spam, malware, or just not trusted by their system. Even if it's safe, Facebook's filters sometimes play it extra cautious—especially with shortened or unfamiliar URLs.

Hey, guys, This error is protected you from spammers and suspicious websites. If anyone having an issue with that issue so don't take stress because you may also get advice or help from genuine facebook experts. This is the real number or facebook experts and it's completely toll-free @+1-888-414-3820 (USA, CANADA)

If facebook realize that it's just a spam or not safe for a user. If the user wants to more info so dial these toll-free number: +1-844-773-9313 (USA, CANADA),+44-800-051-3717 (UK),+61-180-082-5192 (AUS)

It's a warning. Fb is guarding against hackers...

It also happen when the link or site you shared is not secured with ssl certificates or their ssl might be expired. Browsers always show such errors if the site is not secured with the ssl certificates that browsers accept.

Wincer is right, it is just because it is an outgoing link. Facebook is just letting you know you are being redirected to another website.

May be you are sending spam message or technical problem in your account.

because it may be spam
or it is registered as spam in facebook

Because the link is outgoing, fb suggest their members to double check the link.