Both the DXF and STEP CAD files are pretty common, so you should have no trouble in finding a program that is capable of convert DXF drawings to ISO STEP format.
Convert AutoCAD DXF Drawing Exchange Format to ISO-10303 STEP product data.
We found 16 software records in the database related to .dxf to .step file format conversion.
Microsoft Windows software - convert dxf to step on Windows
A 2D and 3D CAD construction software
Convert from dxf file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned dxf to step. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A PLM/CAD/CAM/CAE software suite
Autodesk Inventor is modeling application used to create 3D digital prototypes.
A 3D modelling software
Leading 2D and 3D CAD development software from Autodesk
A CAD converter with huge format support
A 3D modelling application
A widely-used 3D animation application from Autodesk
Apple macOS / Mac OS X software - convert dxf to step on OS X
Mac version of popular Autodesk AutoCAD software
Multiplatform software - convert dxf to step on any platform
3D CAD/CAM tool for product development
An open source multiplatform 3D CAD/MCAD/CAx/CAE/PLM modeler