The Colombian international believes that Vidic signals the start of a new era, where Inter will challenge for the Serie A title again.
"He's an important signal for the start of the new president's project," Guarin told Tuttosport. "A champion with years of experience as captain of Manchester United.
"He's a player who will do well on and off the field. His presence will also be essential for all the youngsters who have come this year and will come in the future.
"Vidic was just the man this Inter needed."
Guarin is reportedly close to signing a new deal at Inter, having been linked with a move away in January.