tinymce-docs-4x/_includes/configuration/force-p-newlines.md

force_p_newlines (deprecated)

This option is deprecated as of version 3.5 use forced_root_block: false instead to control p vs br behavior.

This option enables you to disable/enable the creation of paragraphs on return/enter in Mozilla/Firefox.

Type: Boolean

Default Value: true

Possible Values: true, false

tinymce.init({
  selector: "textarea",  // change this value according to your html
  force_p_newlines : true
});