Ahead of the sides' clash in Bathurst on Saturday, Marshall said Utoikamanu was happy at the Tigers, where he is a vital cog in their ongoing rebuild.
On Wednesday, the Panthers granted triple premiership-winning prop Fisher-Harris a release from his contract to return to New Zealand on compassionate grounds.
He will join the Warriors from 2025.
Fisher-Harris's shock exit will clear more than $900,000 from the Panthers' salary cap for next season and transforms Ivan Cleary's side into a major player in the transfer market.
The Panthers could use some added muscle in the middle, not least because Spencer Leniu also left last off-season, but few elite props are coming out of contract next year.
NSW representative Utoikamanu is under contract through 2025 but has a get-out clause that can be triggered if he misses State of Origin selection or the Tigers fail to play finals in 2024.
Utoikamanu has been linked with the all-conquering Panthers but as far as Marshall is concerned, the player is unable to negotiate with the cashed-up Panthers until the end of the season at the earliest.
"The fact of the matter is he's still on contract here next year," Marshall said.
"I know there's clauses in his contract but they can't talk to him until November. I'm not worried about it."
Long tipped as a future star, Utoikamanu has formed a fearsome front-row pairing with David Klemmer during the Tigers' 2-3 start to the season.
The 23-year-old is averaging 112 run metres and 29 tackles per game under rookie coach Marshall, who flagged his representative credentials after the Tigers beat Parramatta earlier this month.
"It's probably been the best footy he's played in his career," Marshall said of Utoikamanu's recent form.
"You've got to be happy to play good footy. He's expecting a baby pretty soon and his life's going good.
"His footy's doing the talking and that's probably the biggest thing.
"But he's definitely in the top two or three front-rowers in the game at the moment.
"We see him as a long-term prospect for us. We've expressed that to him."
The Tigers welcome rookie five-eighth Lachie Galvin back from suspension to face the Panthers, whose own No.6 Jarome Luai faces his future club for the first time since agreeing terms.
Penrith's Taylan May misses the match for a personal matter, which the Panthers told AAP was unrelated to the car hooning video the centre posted to his social media this week.
The omission paves the way for ex-Canterbury flyer Paul Alamoti to make his club debut.
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