Cleveland.com's Mary Kay Cabot tweeted Rosenhaus' full statement:
Also, Njoku tweeted, "I'm all in Cleveland. Time to work."
Last month, Rosenhaus told ESPN's Adam Schefter, "It is in David's best interest to find a new team at this time," after the Browns signed tight end Austin Hooper to a big contract in free agency.
The Hooper deal is worth $42 million over four years with a $10 million signing bonus and $23 million in guaranteed money.
Cleveland selected Njoku with the No. 29 overall pick in the 2017 NFL draft in hopes that he would quickly develop into one of the NFL's top tight ends. Early returns were good.
As a rookie, Njoku showed flashes with 32 receptions for 386 yards and four touchdowns. He then parlayed that into a career year in 2018 with then-rookie Baker Mayfield as his quarterback, finishing with 56 receptions for 639 yards and four scores.
Hopes were high for Njoku entering the 2019 campaign, as the Browns added wide receiver Odell Beckham Jr. and running back Kareem Hunt to an offense that already featured Mayfield, Njoku, wide receiver Jarvis Landry and running back Nick Chubb.
Njoku suffered a broken wrist in Week 2, however, and he was ineffective when he returned from the injury later in the season.
All told, Njoku made only five catches for 41 yards and one touchdown in four games.
The decision to sign Hooper suggested that the Browns were either ready to move on from Njoku or place him in a lesser role. Cleveland did exercise the fifth-year option in Njoku's contract in April, though, meaning he is under contract through 2021.
It may be difficult for Njoku to put up big numbers in 2020 if Hooper stays healthy, as he is now behind Hooper, Beckham, Landry, Chubb and perhaps even Hunt as far as the Browns' offensive options go.
His presence gives the Browns one of the most athletic and dynamic tight end tandems in the game, however, and it could be the key that unlocks the formula Cleveland needs to end its 17-year playoff drought.