The striker left the Scottish champions at the end of last season following a successful six-year spell at Parkhead.
However, the Greece international could now be back at the club where he won four league titles, two Scottish Cups and the Scottish League Cup.
"Samaras had a great career at Celtic but we'll see. We'll look at the whole picture," Deila told the Sunday Mail. "I have not decided yet and there are many players on our list.
"I never close the door on anything. I haven't spoken to Samaras because he has been in Brazil."
Samaras and his Greece teammates recently reached the last 16 of the World Cup before being knocked out by Costa Rica.