The U.S. has reiterated its offer of assistance to Cuba in exchange for "fundamental changes" to its communist political regime after CIA director John Ratcliffe visited the Caribbean island nation on Thursday.

Ratcliffe's trip is thought to be only the second time the head of the U.S. intelligence service has been to the country since its 1959 communist revolution.

The CIA director delivered a message to top Cuban lawmakers, according to news agency Reuters, stating that Washington would "seriously engage" with the country's government — but "only if it makes fundamental changes."

On Thursday, the CIA posted photos on social media of Ratcliffe in the Cuban capital, Havana, with no context.

CNBC reached out to the CIA for comment.