The 26-year-old bemoaned a lack of opportunities with the relegation-threatened side after failing to score in six appearances.
Teerasil, who also had a trial at Atletico Madrid and signed but never played for Manchester City, said the language barrier had proved too great an obstacle to overcome.
"I had a lot of problems particularly communications with the coach and team mates and that made it difficult for me to understand the team's tactics," he was quoted as saying by the Bangkok Post.
"It was not that I did not try. I did fight for a place but it was fruitless. I don't want to just sit and watch my team mates play. I will go back to Thailand probably at the end of this month and play for Muangthong."
Teerasil's stint in Europe meant he missed Thailand's successful Suzuki Cup campaign, where the War Elephants became Southeast Asian champions for the first time in 12 years by beating Malaysia 4-3 on aggregate in the final.
The return of the striker, who has scored almost 30 goals for his country, was welcomed by national team manager Kiatisuk Senamuang with World Cup and Asian Cup qualifiers starting later this year.
Thailand will host South Korea, Uzbekistan and Honduras in the King's Cup next month as they continue preparations for their bid to qualify for both.
"Everyone wants to see him play for the national team. His presence would make us stronger," Kiatisuk was quoted as saying by the newspaper.
(Writing by Patrick Johnston in Singapore; Editing by John O'Brien)
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