US teenager Coco Gauff crushed Italy's Martina Trevisan 6-3 6-1 on Friday to become the youngest French Open finalist in 21 years, setting up a showcase clash with world number one Iga Swiatek.

But before she left the court, Gauff used her platform to appeal for an end to gun violence in her home nation, writing on the on-court camera: "Peace End Gun Violence".

The United States has experienced a number of mass shootings over the past few weeks.

Four people were killed at a Tulsa medical building in Oklahoma on Thursday, barely a week after 19 children and two teachers were shot dead at an elementary school in Uvalde, Texas.

Gun violence is a personal issue for Gauff, who said she had friends who survived the 2018 mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida.

"For me, it's kind of close to home: I had some friends that were a part of the Parkland shooting," she said.

"I just think it's crazy. I think I was maybe 14 or 13 when that happened, and still nothing has changed."

The Parkland shooting left 17 students and staff members dead.

Events like that that put tennis into perspective for Gauff.

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"I think I'm in a mind now, like, [tennis] does not matter," she said.

"Yeah, it's a grand slam final, but there are so many things going on in the world right now, especially in the United States. I am not going to stress over a tennis match.

"I woke up this morning and I saw there was another shooting and I think it's just crazy.

"That was just a message [I wrote on the camera] for people at home to watch, and for people who are all around the world to watch.

"Hopefully it gets into the heads of people in office to change things."

The 18-year-old, who had not dropped a set on her way to her first grand slam final, will face Polish top seed Swiatek, who cruised through her semi with a 6-2 6-1 demolition of Russian Daria Kasatkina to stretch her winning run to 34 matches.

She is also through to the women's doubles semifinal alongside Jessica Pegula.

"Playing Iga, she's on a streak right now obviously," Gauff said. 

"And I think, going in, I have nothing to lose and she's definitely the favourite going into the match on paper.

"I'm just going to play free and play my best tennis. I think in a grand slam final anything can happen.

"If I do lift the trophy, honestly, I don't think my life is going to change.

"I know it sounds kind of bad to say that, but the people who love me are still going to love me regardless if I lift the trophy or not."

Reuters/ABC