The 22-year old Estonian striker was the subject of a bid believed to be from Lech Poznan but the Steelmen were forced to reject their advances.
"We understand there is likely to be a considerable amount of interest in Henrik given just how well he has performed since arriving at the club in January 2012,” said Motherwell chief executive Leeann Dempster.
"He scored five goals in his first seven matches after joining the club and created more goals than any other player in the Scottish Premier League last season; that obviously hasn't gone unnoticed.
"However, the bid we have received does not match our valuation of the player."
Since arriving at Fir Park from Finnish club RoPS in January 2012, Ojamaa has scored 11 league goals in 55 appearances as well as providing 17 assists.