The Senegal international midfielder has struggled to claim a regular starting place in Chris Coleman's side this season and did look likely to leave Fulham for Wigan during the January transfer window.
However, Diop truned down the opportunity of a move to the JJB Stadium with the intent on regaining his place in the Fulham side.
"I want to prove myself in the remaining matches this season," Diop told the Daily Star.
"I have been preparing for the Portsmouth game next week. My aim is to get fitter and stronger."