The Frenchman impressed in defeat to Kawasaki Frontale today.
Lampard said, "Kurt is a very good defender, a very good person and professional, and I want him here, simple as that. We are competitive with the centre-backs we've got in the team.
"He had a very good season at Everton and I understand why they want him, but he's a Chelsea player and I want him. He's working really hard and if he competes for a position and plays well this season then he plays."