That view has not changed even though Martial featured for the first time since interim United boss Rangnick took charge when he came on as a substitute in Saturday’s 1-0 win against West Ham.
Martial has made 11 United appearances this season, scoring a single goal, against Everton on 2 October.
United are yet to decide whether to accept the offer.
Sevilla are challenging for the La Liga title and currently second in the table, four points behind leaders Real Madrid with 16 games remaining.
Martial is one of a number of United players with uncertain futures.
Jesse Lingard is still wanted by Newcastle, although BBC Sport has been told reports the Magpies have offered a £10m loan fee for the England international, whose contract expires in the summer, are wide of the mark.
Goalkeeper Dean Henderson, 24, is also looking to try to find regular football after losing out to David de Gea in the battle to be United’s number one.
The Premier League winter transfer window closes at 23:00 GMT on 31 January.