Blake, 21, is set to be in Wales' squad for their 23 May friendly in Croatia, but he hopes to turn the call down.
"No disrespect but hopefully I can't make it as I hope to be playing for Cardiff in the play-off final the day before," said Blake.
Cardiff are bidding to end their 48-year exile from the top flight.
Dave Jones' men travel to Leicester City for the first leg of their play-off semi-final on Sunday, before Wednesday's return at the Cardiff City Stadium.
The winner of the two-legged tie will face the winners of the Nottingham Forest and Blackpool clash in the Championship play-off final at Wembley on Saturday, 22 May.
Blake has been hailed as Cardiff's form player by his team-mates as an unbeaten 10-game run - including seven victories - sealed City's top-six spot.
The Wales Under-21 international's mature performances for the Championship high-fliers are all the more impressive, as it has been Blake's first run of first-team football since following Aaron Ramsey, Joe Ledley and Chris Gunter out of Cardiff's youth academy.
Blake is one of nine Welsh internationals in Championship play-off action, so Toshack will delay naming his squad to play Croatia in Osijek the day after the Wembley showpiece.
Joe Ledley and Adam Matthews would normally join Cardiff team-mate Blake in the Wales squad if the Croatia game did not clash with the play-offs, while midfielder Andy King is pivotal to Leicester's play-off bid.
Striker Rob Earnshaw and defender Chris Gunter are Forest regulars, while Blackpool require Wales trio Neal Eardley, David Vaughan and Rob Edwards.
But Blake hopes his Cardiff form can earn him a senior Wales call when their 2012 European Championship qualifying campaign starts in Montenegro in September.
"Doing well in the play-offs is so important to the club and me as a Cardiff fan, so that is my main focus at the moment," Blake told BBC Sport.
"But it will be a great honour to play for Wales and I can't wait to get my first cap. Although I've done okay recently, I need to fully establish myself in the Cardiff team first.
"Hopefully I can follow my mates from the Under-21s like Andy King, Jack Collison and Aaron Ramsey into the senior team.
"John Toshack has consistently said players need to be playing regularly whatever league they're in to earn a senior call.
"I've now played 13 games on the bounce and not just in the lower-leagues, in a good team pushing for a place in the Premier League and I think I've done well.
"And winning promotion to the Premier League and winning my first Wales senior cap be a great double achievement this year - it doesn't get much better than that."
It could be a dream season's end for Blake in a campaign that started badly for the youngster from the Gwent Valleys.
Blake, a lifelong Bluebirds fan, feared his Cardiff career was over in August when he was farmed out on loan to Championship rivals Plymouth in an attempt to improve his "bad attitude".
"The season didn't start well as I played just once in pre-season as I came from injury," said Blake.
"Then I went to Plymouth on loan and I thought that was the end of me at Cardiff.
"I was going to sign at Plymouth until the end of the season but couldn't as they had a transfer embargo on them."
Parent club Cardiff's well-documented financial trouble and subsequent self-imposed transfer embargo actually benefited Blake, as he was required when they suffered their mid-season injury crisis.
It was Blake's "second January blessing in disguise", as he acknowledges: "If Cardiff were able to sign players in January, I probably would not have got my chance.
"I thought I blew my last chance at Cardiff. But I got another due to the club's financial difficulties. That was a gift as, being a little selfish for a moment, the troubles worked in my favour.
"I used to be late for training, I didn't eat the right foods and as soon as training was over I'd go home and not eat with the boys.
"I was in the squad but not part of it but I've grown up and now I'm doing myself justice.
"My loan move to Plymouth took me out of my comfort zone and was a rude awakening for me.
"I realised I had a great opportunity for a good career at a good club - and Cardiff is the club I wanted to play for since I was little."
Source: BBC Sport
Source: BBC Sport