“Fear cuts deeper than swords,” the tweet read. “Vote. Tuesday the 6th.”
Martin has been critical of Trump in the past.
In an interview with New York Times Magazine last month, Martin compared the President to the show’s character King Joffrey, a tyrannical teenage ruler on the series.
“They have the same amount of emotional maturity,” Martin said.
Cast member Maisie Williams also weighed in on Trump’s reference to the series on which she stars, but kept her point brief.
“Not today,” she wrote.
(HBO and CNN share parent company WarnerMedia)