West Yorkshire Police received more than 300 complaints about a speech earlier this month in Leeds in which he said Israeli tourists were not welcome in the city where he has a constituency.
Detectives travelled to London to speak to him and he is understood to have denied being anti-Semitic.
Mr Galloway said: "This is an absolute and despicable attempt to curb my freedom of speech by people who appear to be quite happy about the indiscriminate murder of Palestinians.
"I won't be silenced, I will keep speaking out against horrendous injustice."
He is understood to believe no prosecution for inciting racial hatred will follow his comments. He is thought to have told police that Israel was not a race.
The Crown Prosecution Service will decide whether any charges should be made.
West Yorkshire Police Chief Superintendent Paul Money said: "A 59-year-old man has been interviewed under caution voluntarily following complaints made about the content of a speech in Leeds earlier this month.
"Once inquiries are completed, the matter will be referred to the Crown Prosecution Service for their consideration."