Spain stayed on top of World Cup qualifying Group G with a 2-1 win in Skopje, the striker scoring the visitors' second goal to move on to five for the campaign.
Costa revealed this week he has been told via text message from manager Antonio Conte that he does not have a future at Stamford Bridge, an SMS he then forwarded to the club's hierarchy.
The 28-year-old was keen on a move to former club Atletico Madrid, but their failed appeal against a transfer ban has complicated that option.
AC Milan have been heavily linked with a swoop, while rumours connecting him with the Chinese Super League also persist, despite Costa saying last month he would not make such a switch as it would jeopardise his hopes of playing in the World Cup.
"I don't know," Costa said when asked about his future by TVE.
"I have two years left on my contract with Chelsea, they have to realise what they want to do with me. I have to wait to see what decision the club makes."
Costa insisted Spain knew they were in for a difficult match against Macedonia on Sunday, with David Silva also on target as the visitors moved into a two-goal lead before Stefan Ristovski's second-half strike for the hosts threatened a comeback.
"It was very important to win, we knew it would not be easy — look at the second half," he said.
"In the first half we could have scored more, but the second was complicated. We learned to be together and suffer.
"These are very important games but the match against Italy [in September] is more so. Those of us [nearing a suspension] were very focused and knew how important it was not to see a yellow card."
Costa scored 20 Premier League goals last season as Chelsea won the title in their first campaign under Conte.