Villas-Boas failed to sign Modric and was sacked as Chelsea manager just eight months into his reign.
Modric left Spurs at the end of the same season in 2012 for Real Madrid and Villas-Boas remarkably then replaced Redknapp in the White Hart Lane hot seat.
"Agents will be talking to chairmen at football clubs without the knowledge of the club they belong to," Redknapp told Yahoo Sport UK.
“They'll all be tapping up people, managers ring players.
“He was the manager of Chelsea, it's breaking the rules really isn't it.
“But it was amazing really they got rid of me and gave him the job and he had been tapping up their best player for the last six months.
“There's something not quite right there."