Ferrell and the Mavs came to terms on a two-year, $5.3 million deal Thursday, but the 25-year-old guard reconsidered overnight.
"We felt uncomfortable and will weigh our options," agent Cervando Tejeda told Yahoo Sports on Friday morning.
A team source said Tejeda informed the Mavs of Ferrell's decision after they read the report online. Tejeda declined to comment when reached by ESPN.
Ferrell is an unrestricted free agent because the Mavs rescinded his $2.9 million qualifying offer last week. The team considered that move a formality because it was in the final stages of negotiating the deal to keep Ferrell.
Ferrell joined the Mavs as a G League call-up during the 2016-17 season and performed so well that the team signed him to a two-year contract when his 10-day deal expired.
He has averaged 10.6 points and 3.0 assists in 118 games for the Mavs, including 50 starts. He could have been pushed for playing time by second-round pick Jalen Brunson if Ferrell returned to Dallas.