Those <p>
tags are enabled by default because in most cases you want your Text wrapped in propper HTML markup. However, typing your question into google, gets me to this two lines of Typoscript, wich I just tested on a 6.1.7 and which seem to do the job:
tt_content.stdWrap.dataWrap >
lib.parseFunc_RTE.nonTypoTagStdWrap.encapsLines >