The Leeds-based North East Counter Terrorism Unit said it was aware that large numbers were heading out to the Middle East “for a variety of reasons”.
The comments were made in response to a BBC story which suggested Kurds living in West Yorkshire had travelled to Iraqi Kurdistan to join Kurdish forces fighting against Islamic State militants.
One Kurdish woman told the BBC she knew of 20 young men from West Yorkshire and Manchester who had gone to fight.
It is believed hundreds of Britons have gone to Syria or Iraq to fight with extremist groups.
Earlier this week Prime Minister David Cameron said there was a “fundamental difference” between fighting for the Kurds and joining Islamic State.
Home Office advice is that taking part in an overseas conflict could be an offence under terrorism laws.
A spokesman said: “However, UK law makes provisions to deal with different conflicts in different ways - fighting in a foreign war is not automatically an offence but will depend on the nature of the conflict and the individual’s own activities.”
Kurds living in Yorkshire are urging their countrymen living in Britain to stay at put.
Ali Wartty, a law graduate who has made Sheffield his home, said the vast majority of Kurds living in Britain opposed Islamic State.
He said poorly-educated men aged between 18 and 25 were susceptible to “brainwashing” although he isn’t aware of anyone who has travelled to Kurdistan to fight for either side.
A spokeswoman for the North East Counter Terrorism Unit said: “We are aware that large numbers of British nationals are travelling to the Middle East. These people are from across the UK and this problem is not specific to a particular area.
“We do know that some of those travelling are from Yorkshire. However, we would not provide a breakdown of how many there are or where they are from.
“While these people may be travelling for a variety of reasons, travel to the Middle East for any purpose is extremely unsafe and strongly discouraged.
“Anyone who is concerned about a friend or loved one who is planning to travel should come forward and speak to police. You can call local police on 101 and they’ll talk with you in confidence.
“People can help those in the Middle East safely and legally by donating to UK registered charities with ongoing relief operations. The Charity Commission’s website should be used to check that a charity is registered and that donations will be used properly.”