"I didn't like the physical nature of the game in England or the referees who let more things go, and who blow for fewer fouls than they do here," Morientes said as reported by Sky Sports on Thursday.
Morientes, who only scored 12 goals in 61 appearances at Liverpool complained the English style of play was too combative.
"A striker isn't protected from rival defenses there, and they gave me a really hard time."
The 30-year-old joined Valencia in July for a reported fee of six million Euros.
"I wanted to return to what I knew and play the kind of football in which I felt more comfortable," said the former Real Madrid ace.
Indeed, Morientes proved he was more familiar with Spanish football, scoring two goals in two league games, and a hat-trick in the Champions League against Olympiakos.
Morientes is expected to start on Sunday when Valencia visit champions Barcelona in the Primera Liga.