I read about the new version of the digital elevation model at 30 meters (SRTM 30 meters), but I can not find from were I can download it.
There is a new, 30 meters resolution SRTM DTM coming out. As stated on the NASA JPL official page,
The next release is planned for later in 2014, and it is expected to include all of South America plus North America south of the United States.
It is incomplete, for now, it has only limited coverage. You can read an article about SRTM coverages here (it's kind of outdated though). You can download the data published so far from the USGS EROS Center's EarthExplorer application (Digital Elevation -> SRTM -> SRTM 1 Arc-Second Global).
I answered a similar question here
You can download and clip a portion of the SRTM 30m DEM with one command with the elevation Python command line tool.
Install it and perform the self check with:
$ pip install elevation
Check if you have all the dependencies installed (mainly GDAL tools):
$ eio selfcheck
Download and clip a portion of the SRTM 30m DEM giving bounding box as WGS84 coordinates:
$ eio clip -o Rome-DEM.tif --bounds 12.35 41.8 12.65 42