Facebook also said that it would respond to candidates or parties making premature claims of victory or contesting declared outcomes by adding labels and notifications with authoritative information about the state of the race.
It said it would temporarily stop running political ads in the United States after polls close on November 3.
Alphabet Inc's Google last month also said it would block election-related ads after the polls closed for an indefinite period. Facebook had previously said it would stop accepting new political ads in the week before Election Day and would reject ads prematurely claiming victory.
Republicans are mobilizing thousands of volunteers to watch early voting sites and ballot drop boxes, part of an effort to find evidence to back up President Donald Trump's unsubstantiated complaints about voter fraud.
The president's son Donald Trump Jr. sought such volunteers for an "Army for Trump's election security operation" in a September video that racked up millions of views on social media.
Facebook's Vice President of Content Policy Monika Bickert said the company would not apply its new policy retroactively, but confirmed that the video would be considered in violation of its rules going forward.
"Under the new policy, if that video were to be posted again we would indeed be removing it," she said on a call with reporters.