Approach the classmate before the next class. Ask him politely to stop being disruptive in class. Explain that the noise makes it difficult to concentrate and that it disrupts both his and your learning.
Write down the names of the noisy students if they do not respond to your request. If you don't know their names, write down their description and where they sit.
Talk to the professor at the end of class. Tell the professor the name of the classmate or provide a description. Explain to your professor that despite your attempts at asking the students to quiet down, their noise level continues to make it difficult to concentrate.