Steve Lomas says there have been no offers for Francisco Sandaza and doubts Rangers would be able to afford the St Johnstone striker.
Sandaza has impressed since joining the Saints on a one-year contract last summer and he is attracting interest from several countries.
The Spaniard's agent claimed earlier this week that Sandaza is likely to reject an offer to stay at McDiarmid Park in favour of moving to a bigger club at the end of the season.
Saints boss Lomas is unhappy with the forward's representative, but has challenged the former Brighton man to win a move to the English Premier League.
Lack of courtesy
"I have told Fran that if he scores 25 goals this season they will be worth their weight in gold in the summer," said Lomas in the Daily Record.
"Fran could play in the Championship. But I'd say to him, 'If you want to gamble by not re-signing for us then go and score 25-30 goals and a Premiership club will come for you'.
"As long as he keeps his focus and form up he can go in the summer with my blessing."
Lomas added: "There are no offers in and from what I understand Rangers don't have any money anyway.
"It was a real lack of courtesy to read comments from Fran's agent when he hasn't spoken to me. He gives agents a bad name."