His wife, Hema Malini, also extended her best wishes to the actor who is hospitalised after testing Covid-19 positive.
The 84-year-old star said he is sure his "courageous younger brother" will bounce back in no time.
"Amit, get well soon. I am sure of my courageous younger brother... he will soon be fit and fine in a day or two..." Dharmendra wrote on Twitter.
Dharmendra also extended support to Jaya, his Guddi co-star.
"Jaya, don't worry... everything will be fine my brave baby... Look after yourself and everyone at home... Love you all... take care," he added.
Dharmendra's wife, actor-MP Hema Malini also took to Twitter to wish good health to Amitabh.
"Amit ji has tested positive & has been admitted to Nanavati hospital. I pray for his well being & I'm sure that with all our collective prayers, he will come out of this safely (sic)" Malini, who has worked with the actor in films like Sholay, Trishul, Baabul, Baghban among others, said.
- Dharmendra Deol (@aapkadharam) July 12, 2020
- Hema Malini (@dreamgirlhema) July 12, 2020