Steve Kerr said this season's NBA title was the toughest by far after the Golden State Warriors claimed back-to-back championships on Friday.

Reigning champions the Warriors outclassed the Cleveland Cavaliers 108-85 in game four to seal a series sweep on the road at Quicken Loans Arena.

Kevin Durant was named Finals MVP for the second successive season as the Warriors won their third title in four years.

The Warriors were forced to do it the hard way after facing elimination against the Houston Rockets in the Western Conference finals, while Stephen Curry, Draymond Green and Durant all spent time on the sidelines throughout the campaign.

Speaking amid the celebrations, Warriors head coach Kerr told ESPN: "This was the hardest year we've had of the three championships by far.

"Just the length of the journey. These guys are not just incredibly talented but they're selfless.

"They love each other, they play for each other and you can see the result."

While Durant posted a triple-double with 20 points, 12 rebounds and 10 assists and Curry scored 37 points, Kerr heaped praise on Klay Thompson.

All-Star Thompson had 10 points and six rebounds for the Warriors in Cleveland.

"He is a machine. He keeps coming. Every day he is defending the best player on the other team," Kerr said.

"He is running off screens like Reggie Miller. He is just a machine. He is there for us every day."

Kerr and Curry shared a warm embrace after the Warriors clinched another title against the Cavaliers.

Asked about that moment, two-time MVP Curry said: "He [Kerr] talked to us at the beginning of the year about everything we have to go through.

"I know it's a game and basketball but all the sacrifice and the trials and tribulations you go through during the season to get to his point.

"And for him especially. We know what he's been through physically in the last three years. For him to fight through that and be there for us every single day and for us to celebrate this moment makes it all worth it."