The suit asked the court to declare it illegal to intimidate voters at the polls.
Similar suits have been filed in Arizona, Nevada, Pennsylvania, North Carolina, and Michigan.
On Thursday, the campaign promised not to intimidate voters on Election Day and instructed campaign workers on how to behave properly at the polls.
As Election Day draws near, at least some faction within the campaign appears eager to avoid accusations that Trump supporters suppressed minority votes by scaring them out of casting a ballot.
(For example, Trump told a crowd in Akron, Ohio, “And when I say ‘watch,’ you know what I’m talking about right?
It also applies to close Trump adviser Roger Stone, who has organized poll-watching activities, and the “officers, agents, servants, and employees” of Trump and Stone.
Voter fraud has been a popular theme among Republicans this year, from Trump to state Republican leaders who cite fraud as a reason to make it more difficult to vote.
But as Friday’s ruling shows, it’s a lot easier to warn about fraud on the campaign trail than in front of a judge.
The restraining order is the result of a lawsuit filed by the Ohio Democratic Party against Trump, Stone, and the Ohio Republican Party.