"Evan's health is good, and he is grateful for the outpouring of support from around the world," Tucker said in the letter, a copy of which was seen by Reuters.
"Evan's family ... are relieved to know we finally have contact with Evan," she said, adding she was encouraged by the meeting. Last Thursday a Moscow court remanded Gershkovich in pre-trial detention until May 29 on charges that carry a prison term of up to 20 years.
He has appealed the detention through his lawyers, as Washington said it was pushing hard to secure his release.
A state-appointed official said on Monday he had visited Gershkovich at Moscow's Lefortovo prison, the main pre-trial jail for high-profile suspects and those charged with espionage or treason.
"We continue to call for his immediate release. The legal avenue is one of several avenues we are working to advocate for Evan's release," said Tucker.
The Wall Street Journal denies the charges. The Kremlin said last week, without providing evidence, that Gershkovich had been "caught red-handed".
(Reporting by Jake Cordell; Writing by David Ljunggren; Editing by Leslie Adler and Daniel Wallis)
