The Huffington Post has a screen shot of the poll. It asks, "Should Obama be killed?" The possible answers are "yes," "maybe," "If he cuts my health care" and "no."
"We are aware of it and we will take the appropriate investigative steps," the Associated Press quoted Secret Service agent Darrin Blackford, as saying.
At least 730 people took part in the user-generated poll before Facebook removed it upon officials learning of its existence.
Results of the survey were not available because the application was disabled. The company said the person who created the poll has been suspended from using the site.
"The third-party application that enabled an individual user to create the offensive poll was brought to our attention this morning," said Barry Schnitt, Director of Policy Communications for Facebook.
"The application was immediately suspended while the inappropriate content could be removed by the developer and until such time as the developer institutes better procedures to monitor their user-generated content. We're working with the US Secret Service but they'll need to provide any details of their investigation," he added.
Secret Service spokesman Ed Donovan confirmed to CBS News that the Secret Service and Facebook are working together on the issue.