Are you talking specifically about the crown of thorns? Or the crucifixion? They're connected but not the same. The trial and crucifixion were absolutely at the behest of the Jews, but the specific act of making the crown of thorns is not attributed in the Bible to anyone other than the Roman soldiers.

Matthew 27:27-30:
"Then the soldiers of the governor took Jesus into the Praetorium and gathered the whole Roman cohort around Him. And they stripped Him and put a red cloak on Him, and after twisting together a crown of thorns, they put it on His head, and put a reed in His right hand; and they knelt down before Him and mocked Him, saying, ‘Hail, King of the Jews!’ And they spit on Him, and took the reed and beat Him on the head."

Mark 15:16-19: "The soldiers took Him away into the palace (that is, the Praetorium), and they called together the whole Roman cohort. And they dressed Him in purple, and after twisting together a crown of thorns, they put it on Him; and they began saluting Him: ‘Hail, King of the Jews!’ And they repeatedly beat His head with a reed, spit on Him, and knelt down to pay false homage to Him."

John 19:1-3: "So Pilate then took Jesus and had Him flogged. And the soldiers twisted together a crown of thorns and placed it on His head, and put a purple cloak on Him; and they repeatedly came up to Him and said, ‘Hail, King of the Jews!’ and slapped Him in the face."