Iran are trying to lift the trophy for the first time since 1976 and reached the last four after beating pre-tournament favourites Japan 2-1.
South Korea or Jordan await the winners in Saturday's final.
Ghalenoei will on Wednesday welcome back Mehdi Taremi from suspension after the Porto striker was sent off in Iran's last-16 win over Syria on penalties.
Taremi is 31 and could be playing at his last Asian Cup, with team-mates Saman Ghoddos, Sardar Azmoun and Alireza Jahanbakhsh all of similar age.
Ghalenoei urged them to "use the opportunities that you have (left)".
"For some of the players, maybe it will be the last dance," said the coach on Tuesday.
"We are standing at a very sensitive part of history - we have a very good chance to make history for Iranian football and the Iranian people.
"We have to use the opportunity and give everything to beat Qatar and reach the final."
Iran came roaring back from a goal down in the quarter-finals to beat Japan.
They won it with a 96th-minute penalty after Iran's relentless attacking unsettled the Japanese defence.
Ghalenoei urged his players to "forget about Japan" and focus on 2019 champions Qatar.
"We have to be even more concentrated than we were against Japan and we have to cover even more distance," he said.
"I hope we can reach our first final in almost 50 years. I have big belief in our players that they can do this."
'Complex game'
Like Iran, Qatar breezed through the group stage with three wins. They then beat Palestine inside 90 minutes.
But they had to go to extra time and penalties to see off Uzbekistan in the quarter-finals, and coach Tintin Marquez said the semi-final will be "a complex game".
"We are one step away from the final for the second time in a row," said the Spaniard, who took over from Carlos Queiroz only a month before the tournament began.
"We recognise how difficult this game will be. I didn't know that Iran hadn't won it for such a long time but we know we will be facing a tough team."
Iran have scored 10 goals at the tournament so far and can call on Europe-based attackers such as Taremi, Feyenoord's Jahanbakhsh and Roma's Azmoun.
Qatar have their own star player in four-goal forward Akram Afif and defender Tarek Salman said they will not fear reputations.
"They have stars who play in European leagues and this gives us an incentive to give 200%," he said.
"I hope we will bring joy to our fans."
