The Eredivisie club say they have not received 30% of Vorm's transfer fee, which they claim was agreed as part of his deal to join Swansea in 2011.
The 30 year old moved to White Hart Lane last month, for what Swansea said was an undisclosed fee.
Swansea are not commenting on Utrecht's claim.
However Wilco van Schaik, general manager of FC Utrecht, told BBC Wales he has been told by the Premier League club's chairman Huw Jenkins, that Swansea let Vorm go "for free".
"That's unbelievable and unacceptable," said Van Schaik.
"Michel is a very reliable goalkeeper in the Premier League. He is 30 years old, in the prime of his life. He still had a two-year contract and has a good reputation.
"Besides that he's a solid member of the Dutch squad. We want to have the 30% as we agreed."
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