DeFreitas, who has made 33 Test appearances for England, is leaving Lancashire because his two-year-old daughter suffers from asthma and he wants to be closer to his wife's parents, who live near Burton-on-Trent.
Worcestershire are keen to strengthen their attack after releasing the injury-prone West Indian fast bowler Ken Benjamin and re-signing Australia's Tom Moody as their overseas player.
The cricket committee chairman, Mike Jones, said: 'We want to talk to him. With Moody back here we feel that DeFreitas would complete the balance of our side.'
The captain, Tim Curtis, said: 'A big plus in our favour is that the wicket at New Road always give some help to seam bowlers like DeFreitas.'
Derbyshire have also confirmed they are interested in signing DeFreitas and they have been given permission to approach the 27-year-old. Their captain Kim Barnett said: 'We are very hopeful that he will sign. He would improve our team.'
Derbyshire have financial problems after last summer's crisis which almost bankrupted the club, but Barnett insisted: 'Phillip would fit into our wage structure.'Reuse content