After watching Anthony Stokes' 87th-minute free-kick give his side victory over Dundee United in their Scottish Premiership clash at Tannadice, Lennon said: "We made a bid today (for Tomlin) and it was rejected. I don't know where we are at the minute with that.
"Buttner is a player who came to our attention in the last day or so. I have seen him play in midfield or on the left side, or off the striker.
"I would like him to play further forward through the middle. He is a really intelligent footballer with a big build, a very good footballer.
"I don't know how far we are down the line with enquiries. I will know a bit more later on.
"We have other irons in the fire but how far down the line we are with them I don't know.
"Teemu has signed, Nir has signed, we are looking to get one or two more in."
Hoops left-back Emilio Izaguirre threw his jersey to the crowd after the game but Lennon denied it was a goodbye gesture.
The former Celtic skipper, who admitted striker Tony Watt may be allowed to go on loan with Belgian side Lierse and Aberdeen thought to be in the frame, said: "Emilio is not leaving, he is not going anywhere.
"We only have one recognised left-back.
"He has been fantastic for me, he has played a lot of football and I need competition and cover there."
- Sports & Recreation
- Scottish Premiership
- Teemu Pukki
- Anthony Stokes
- Dundee United
- Celtic Park