The last abortion clinic in Kentucky found an unlikely ally this week: The U.S. Justice Department.

Government lawyers on Wednesday asked a federal judge to ban protesters from a small area outside E.M.W. Women’s Surgical Center in Louisville, citing fears that activists from a stridently antiabortion organization gathering for a conference next week could try to block women from entering the facility.

The group, Operation Save America, has a history of extreme antiabortion activism and in May staged a blockade of the Louisville clinic, leading to the arrest of several members. Leaders of the Texas-based group have said there are no plans to mount any acts of civil disobedience next week, when hundreds of members will gather in Louisville for the group’s annual conference.

Still, government lawyers and abortion rights advocates say the precautions are necessary. The government lawyers are seeking a court order that would create a “buffer zone” extending from the clinic’s front door to the curb, where patients are frequently dropped off.

Reproductive rights advocates praised the actions from Justice Department officials and the local U.S. attorney, which came despite Attorney General Jeff Sessions’s personal opposition to abortion.

“These extremists are testing law enforcement on the ground in Louisville and they are testing the Department of Justice to see if they are in fact going to enforce the law,” said Vicki Saporta, president of the National Abortion Federation, an organization of abortion providers. The court filing and a previous lawsuit “sent a clear signal” that the law will indeed be enforced, she said.

But the legal maneuvers drew criticism from leaders of Operation Save America, who pledged to fight the request in court.

“By creating this buffer zone, it restricts us,” said Joseph Spurgeon, a pastor and local leader of the group. “We want to be able to hand women tracts and pamphlets with other resources, to offer them financial assistance, to offer to adopt their children. We want to be able to converse with them one-on-one.”

The conflict heightens tensions in Louisville, which has become a magnet for abortion foes who see the potential to make Kentucky the first state in the country without a single abortion clinic.

Other clinics in the state have either closed or stopped providing abortions since Republican leaders began aggressively regulating them. Now, E.M.W. Women’s Surgical Center is wrangling with state regulators in a legal battle that will determine whether it, too, will have to close.

Operation Save America, previously known as Operation Rescue, is a decades-old antiabortion group known for its extreme tactics. (A separate organization currently carries the Operation Rescue moniker.) It is critical of mainstream antiabortion groups, which it considers too timid, and is trying to push Kentucky and other states to outlaw abortion in violation of Roe v. Wade, the 1973 Supreme Court decision that legalized the procedure nationally.

Spurgeon said the group tried to demonstrate the sacrifices that might be necessary for the cause on May 13, when the members staged a blockade of the Louisville clinic. Several members were arrested after linking arms in front of the doors, blocking access to and from the clinic.

That was a “one-time thing,” he said. The group has asked attendees of the conference, which is expected to attract as many as 1,000 people, to keep it civil and law-abiding. He said he expects that it will stay that way — unless people get the sense that federal authorities are trampling on their free speech rights.

“We believe in obeying authorities,” Spurgeon said. Moreover, he said, “our people are not going to rebel against what we’ve asked them to do.”

But Meg Sasse Stern, a volunteer who helps escort women from the sidewalk to the front door, said Thursday that she is unconvinced.

“One person talking to a reporter to say, ‘I promise to be peaceful’ doesn’t mean everyone is going to respect that,” she said.