"Competition is always nice so it's just a pity to see that the competition here will not be the one that could have been," said the German on Thursday, without commenting on the circumstances of the BAR ban.
Honda-powered BAR, cleared of cheating, were dealt a two-race suspension for a breach of regulations following a check of their car's fuel tank and weight at the last San Marino Grand Prix.
They are contemplating legal action to enable them to compete under appeal.
Button set an unofficial lap record in testing at the circuit recently and BAR had fancied their chances in the fifth round of the season.
Schumacher is chasing a record-equalling fifth Spanish win in a row.
Another victory, his seventh at the Circuit de Catalunya, would equal the late Brazilian Ayrton Senna's run of five successive Monaco Grand Prix victories from 1989 to 1993.
The German, who faces a strong challenge from Renault's championship leader and local hero Fernando Alonso in Barcelona after the Spaniard won the last four races, was more focused on soccer on Thursday, however.
Schumacher, recovering from a bout of flu, started off his preparations by appearing on the winning side in a gentle celebrity kickabout organised by Ferrari sponsor Vodafone.
He talked enthusiastically afterwards about FC Cologne, his hometown club who this week secured promotion to the first division.
"I'm a big fan of Cologne and we're back in the first league from next season," he said with a smile. "Otherwise I just love to watch Champions League games.
Just as he would not predict how many races he might win this year after 13 victories in 2004, so Schumacher would not be drawn on his tip for the Champions League final between Liverpool and AC Milan.
"It's going to be a very tough one, both teams when at their best can win," he said.
