He later told Italian news agency ANSA that he would only leave the club if somebody bought him out.
"I believe that if a person is not well liked, they shouldn't stay against the will of others," Sebastiani said.
"For me Pescara is not a job, on the contrary... This is a company of share capital; if someone wants to substitute us, they need to buy our stakes so that we go home."
The defeat to Lazio on Sunday left Pescara four points adrift at the bottom of Serie A and 13 points behind 17th-placed Empoli.
Italian FA president Carlo Tavecchio said on the organisation's website (www.figc.it) that he had telephoned Sebastiani to express his solidarity for what he called "a vile act".
Serie A issued a statement on its website condemning the arson as a "disgraceful act of vandalism".
(Reporting by Silvia Recchimuzzi in Gdynia; Editing by Toby Davis)
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